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Sample records for mri imaging prior

  1. MRI superresolution using self-similarity and image priors.

    PubMed

    Manjón, José V; Coupé, Pierrick; Buades, Antonio; Collins, D Louis; Robles, Montserrat

    2010-01-01

    In Magnetic Resonance Imaging typical clinical settings, both low- and high-resolution images of different types are routinarily acquired. In some cases, the acquired low-resolution images have to be upsampled to match with other high-resolution images for posterior analysis or postprocessing such as registration or multimodal segmentation. However, classical interpolation techniques are not able to recover the high-frequency information lost during the acquisition process. In the present paper, a new superresolution method is proposed to reconstruct high-resolution images from the low-resolution ones using information from coplanar high resolution images acquired of the same subject. Furthermore, the reconstruction process is constrained to be physically plausible with the MR acquisition model that allows a meaningful interpretation of the results. Experiments on synthetic and real data are supplied to show the effectiveness of the proposed approach. A comparison with classical state-of-the-art interpolation techniques is presented to demonstrate the improved performance of the proposed methodology. PMID:21197094

  2. MRI Superresolution Using Self-Similarity and Image Priors

    PubMed Central

    Manjón, José V.; Coupé, Pierrick; Buades, Antonio; Collins, D. Louis; Robles, Montserrat

    2010-01-01

    In Magnetic Resonance Imaging typical clinical settings, both low- and high-resolution images of different types are routinarily acquired. In some cases, the acquired low-resolution images have to be upsampled to match with other high-resolution images for posterior analysis or postprocessing such as registration or multimodal segmentation. However, classical interpolation techniques are not able to recover the high-frequency information lost during the acquisition process. In the present paper, a new superresolution method is proposed to reconstruct high-resolution images from the low-resolution ones using information from coplanar high resolution images acquired of the same subject. Furthermore, the reconstruction process is constrained to be physically plausible with the MR acquisition model that allows a meaningful interpretation of the results. Experiments on synthetic and real data are supplied to show the effectiveness of the proposed approach. A comparison with classical state-of-the-art interpolation techniques is presented to demonstrate the improved performance of the proposed methodology. PMID:21197094

  3. Optimal sampling with prior information of the image geometry in microfluidic MRI.

    PubMed

    Han, S H; Cho, H; Paulsen, J L

    2015-03-01

    Recent advances in MRI acquisition for microscopic flows enable unprecedented sensitivity and speed in a portable NMR/MRI microfluidic analysis platform. However, the application of MRI to microfluidics usually suffers from prolonged acquisition times owing to the combination of the required high resolution and wide field of view necessary to resolve details within microfluidic channels. When prior knowledge of the image geometry is available as a binarized image, such as for microfluidic MRI, it is possible to reduce sampling requirements by incorporating this information into the reconstruction algorithm. The current approach to the design of the partial weighted random sampling schemes is to bias toward the high signal energy portions of the binarized image geometry after Fourier transformation (i.e. in its k-space representation). Although this sampling prescription is frequently effective, it can be far from optimal in certain limiting cases, such as for a 1D channel, or more generally yield inefficient sampling schemes at low degrees of sub-sampling. This work explores the tradeoff between signal acquisition and incoherent sampling on image reconstruction quality given prior knowledge of the image geometry for weighted random sampling schemes, finding that optimal distribution is not robustly determined by maximizing the acquired signal but from interpreting its marginal change with respect to the sub-sampling rate. We develop a corresponding sampling design methodology that deterministically yields a near optimal sampling distribution for image reconstructions incorporating knowledge of the image geometry. The technique robustly identifies optimal weighted random sampling schemes and provides improved reconstruction fidelity for multiple 1D and 2D images, when compared to prior techniques for sampling optimization given knowledge of the image geometry.

  4. Optimal sampling with prior information of the image geometry in microfluidic MRI

    NASA Astrophysics Data System (ADS)

    Han, S. H.; Cho, H.; Paulsen, J. L.

    2015-03-01

    Recent advances in MRI acquisition for microscopic flows enable unprecedented sensitivity and speed in a portable NMR/MRI microfluidic analysis platform. However, the application of MRI to microfluidics usually suffers from prolonged acquisition times owing to the combination of the required high resolution and wide field of view necessary to resolve details within microfluidic channels. When prior knowledge of the image geometry is available as a binarized image, such as for microfluidic MRI, it is possible to reduce sampling requirements by incorporating this information into the reconstruction algorithm. The current approach to the design of the partial weighted random sampling schemes is to bias toward the high signal energy portions of the binarized image geometry after Fourier transformation (i.e. in its k-space representation). Although this sampling prescription is frequently effective, it can be far from optimal in certain limiting cases, such as for a 1D channel, or more generally yield inefficient sampling schemes at low degrees of sub-sampling. This work explores the tradeoff between signal acquisition and incoherent sampling on image reconstruction quality given prior knowledge of the image geometry for weighted random sampling schemes, finding that optimal distribution is not robustly determined by maximizing the acquired signal but from interpreting its marginal change with respect to the sub-sampling rate. We develop a corresponding sampling design methodology that deterministically yields a near optimal sampling distribution for image reconstructions incorporating knowledge of the image geometry. The technique robustly identifies optimal weighted random sampling schemes and provides improved reconstruction fidelity for multiple 1D and 2D images, when compared to prior techniques for sampling optimization given knowledge of the image geometry.

  5. Optimal sampling with prior information of the image geometry in microfluidic MRI.

    PubMed

    Han, S H; Cho, H; Paulsen, J L

    2015-03-01

    Recent advances in MRI acquisition for microscopic flows enable unprecedented sensitivity and speed in a portable NMR/MRI microfluidic analysis platform. However, the application of MRI to microfluidics usually suffers from prolonged acquisition times owing to the combination of the required high resolution and wide field of view necessary to resolve details within microfluidic channels. When prior knowledge of the image geometry is available as a binarized image, such as for microfluidic MRI, it is possible to reduce sampling requirements by incorporating this information into the reconstruction algorithm. The current approach to the design of the partial weighted random sampling schemes is to bias toward the high signal energy portions of the binarized image geometry after Fourier transformation (i.e. in its k-space representation). Although this sampling prescription is frequently effective, it can be far from optimal in certain limiting cases, such as for a 1D channel, or more generally yield inefficient sampling schemes at low degrees of sub-sampling. This work explores the tradeoff between signal acquisition and incoherent sampling on image reconstruction quality given prior knowledge of the image geometry for weighted random sampling schemes, finding that optimal distribution is not robustly determined by maximizing the acquired signal but from interpreting its marginal change with respect to the sub-sampling rate. We develop a corresponding sampling design methodology that deterministically yields a near optimal sampling distribution for image reconstructions incorporating knowledge of the image geometry. The technique robustly identifies optimal weighted random sampling schemes and provides improved reconstruction fidelity for multiple 1D and 2D images, when compared to prior techniques for sampling optimization given knowledge of the image geometry. PMID:25676820

  6. Should the orthodontic brackets always be removed prior to magnetic resonance imaging (MRI)?

    PubMed Central

    Poorsattar-Bejeh Mir, Arash; Rahmati-Kamel, Manouchehr

    2015-01-01

    Request for temporary removal of orthodontic appliances due to medical conditions that require magnetic resonance (MR) imaging is not uncommon in daily practice in the field of orthodontics. This may be at the expense of time and cost. Metal Orthodontic appliances cause more signal loss and image distortion as compared to ceramic and titanium ones. Stainless steel and large brackets in addition to the oriented miniscrews in relation to the axis of magnetic field may cause severe signal loss and image distortion. Moreover, gradient echo and frequency-selective fat saturation MR protocols are more susceptible to metal artifacts. The spin echo and fat-suppression protocols, low magnetic field strength (e.g., 1.5 Tesla vs. 3 Tesla), small field of view, high-resolution matrix, thin slice, increased echo train length and increased receiver band width could be applied to lessen the metal artifacts in MR images. The larger the distance between an appliance and desired location to be imaged, the lower the distortion and signal loss. Decision to remove brackets should be made based on its composition and desired anatomic location. In this review, first the principles of MR imaging are introduced (Part-I) and then the interactions of orthodontic appliances and magnetic field are farther discussed (Part-II). PMID:27195213

  7. Should the orthodontic brackets always be removed prior to magnetic resonance imaging (MRI)?

    PubMed

    Poorsattar-Bejeh Mir, Arash; Rahmati-Kamel, Manouchehr

    2016-01-01

    Request for temporary removal of orthodontic appliances due to medical conditions that require magnetic resonance (MR) imaging is not uncommon in daily practice in the field of orthodontics. This may be at the expense of time and cost. Metal Orthodontic appliances cause more signal loss and image distortion as compared to ceramic and titanium ones. Stainless steel and large brackets in addition to the oriented miniscrews in relation to the axis of magnetic field may cause severe signal loss and image distortion. Moreover, gradient echo and frequency-selective fat saturation MR protocols are more susceptible to metal artifacts. The spin echo and fat-suppression protocols, low magnetic field strength (e.g., 1.5 Tesla vs. 3 Tesla), small field of view, high-resolution matrix, thin slice, increased echo train length and increased receiver band width could be applied to lessen the metal artifacts in MR images. The larger the distance between an appliance and desired location to be imaged, the lower the distortion and signal loss. Decision to remove brackets should be made based on its composition and desired anatomic location. In this review, first the principles of MR imaging are introduced (Part-I) and then the interactions of orthodontic appliances and magnetic field are farther discussed (Part-II). PMID:27195213

  8. MRI brain imaging.

    PubMed

    Skinner, Sarah

    2013-11-01

    General practitioners (GPs) are expected to be allowed to request MRI scans for adults for selected clinically appropriate indications from November 2013 as part of the expansion of Medicare-funded MRI services announced by the Federal Government in 2011. This article aims to give a brief overview of MRI brain imaging relevant to GPs, which will facilitate explanation of scan findings and management planning with their patients. Basic imaging techniques, common findings and terminology are presented using some illustrative case examples.

  9. MRI (Magnetic Resonance Imaging)

    MedlinePlus

    ... some MRI exams, intravenous (IV) drugs, such as gadolinium-based contrast agents (GBCAs) are used to change the contrast of the MR image. Gadolinium-based contrast agents are rare earth metals that ...

  10. Diffusion-based spatial priors for imaging

    PubMed Central

    Harrison, L.M.; Penny, W.; Ashburner, J.; Trujillo-Barreto, N.; Friston, K.J.

    2007-01-01

    We describe a Bayesian scheme to analyze images, which uses spatial priors encoded by a diffusion kernel, based on a weighted graph Laplacian. This provides a general framework to formulate a spatial model, whose parameters can be optimized. The application we have in mind is a spatiotemporal model for imaging data. We illustrate the method on a random effects analysis of fMRI contrast images from multiple subjects; this simplifies exposition of the model and enables a clear description of its salient features. Typically, imaging data are smoothed using a fixed Gaussian kernel as a pre-processing step before applying a mass-univariate statistical model (e.g., a general linear model) to provide images of parameter estimates. An alternative is to include smoothness in a multivariate statistical model (Penny, W.D., Trujillo-Barreto, N.J., Friston, K.J., 2005. Bayesian fMRI time series analysis with spatial priors. Neuroimage 24, 350–362). The advantage of the latter is that each parameter field is smoothed automatically, according to a measure of uncertainty, given the data. In this work, we investigate the use of diffusion kernels to encode spatial correlations among parameter estimates. Nonlinear diffusion has a long history in image processing; in particular, flows that depend on local image geometry (Romeny, B.M.T., 1994. Geometry-driven Diffusion in Computer Vision. Kluwer Academic Publishers) can be used as adaptive filters. This can furnish a non-stationary smoothing process that preserves features, which would otherwise be lost with a fixed Gaussian kernel. We describe a Bayesian framework that incorporates non-stationary, adaptive smoothing into a generative model to extract spatial features in parameter estimates. Critically, this means adaptive smoothing becomes an integral part of estimation and inference. We illustrate the method using synthetic and real fMRI data. PMID:17869542

  11. MRI of the brain (image)

    MedlinePlus

    An MRI (magnetic resonance imaging) of the brain creates a detailed image of the complex structures in the brain. An MRI can give a three-dimensional depiction of the brain, making location of problems such ...

  12. Functional Imaging: CT and MRI

    PubMed Central

    van Beek, Edwin JR; Hoffman, Eric A

    2008-01-01

    Synopsis Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled MDCT allow for quantification of presence and distribution of parenchymal and airway pathology, Xenon gas can be employed to assess regional ventilation of the lungs and rapid bolus injections of iodinated contrast agent can provide quantitative measure of regional parenchymal perfusion. Advances in magnetic resonance imaging (MRI) of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized helium imaging, which can allow imaging of pulmonary ventilation and .measurement of the size of emphysematous spaces. PMID:18267192

  13. Automatic Iceball Segmentation With Adapted Shape Priors for MRI-Guided Cryoablation

    PubMed Central

    Liu, Xinyang; Tuncali, Kemal; Wells, William M.; Zientara, Gary P.

    2014-01-01

    Purpose To develop and evaluate an automatic segmentation method that extracts the 3D configuration of the ablation zone, the iceball, from images acquired during the freezing phase of MRI-guided cryoablation. Materials and Methods Intraprocedural images at 63 timepoints from 13 kidney tumor cryoablation procedures were examined retrospectively. The images were obtained using a 3 Tesla wide-bore MRI scanner and axial HASTE sequence. Initialized with semiautomatically localized cryoprobes, the iceball was segmented automatically at each timepoint using the graph cut (GC) technique with adapted shape priors. Results The average Dice Similarity Coefficients (DSC), compared with manual segmentations, were 0.88, 0.92, 0.92, 0.93, and 0.93 at 3, 6, 9, 12, and 15 min time-points, respectively, and the average DSC of the total 63 segmentations was 0.92 ± 0.03. The proposed method improved the accuracy significantly compared with the approach without shape prior adaptation (P = 0.026). The number of probes involved in the procedure had no apparent influence on the segmentation results using our technique. The average computation time was 20 s, which was compatible with an intraprocedural setting. Conclusion Our automatic iceball segmentation method demonstrated high accuracy and robustness for practical use in monitoring the progress of MRI-guided cryoablation. PMID:24338961

  14. Three-dimensional microwave imaging with incorporated prior structural information

    NASA Astrophysics Data System (ADS)

    Golnabi, Amir H.; Meaney, Paul M.; Epstein, Neil R.; Paulsen, Keith D.

    2012-03-01

    Microwave imaging for biomedical applications, especially for early detection of breast cancer and effective treatment monitoring, has attracted increasing interest in last several decades. This fact is due to the high contrast between the dielectric properties of the normal and malignant breast tissues at microwave frequencies. The available range of dielectric properties for different soft tissue can provide important functional information about tissue health. Nonetheless, one of the limiting weaknesses of microwave imaging is that unlike conventional modalities, such as X-ray CT or MRI, it inherently cannot provide high-resolution images. The conventional modalities can produce highly resolved anatomical information but often cannot provide the functional information required for diagnoses. Previously, we have developed a regularization strategy that can incorporate prior anatomical information from MR or other sources and use it in a way to refine the resolution of the microwave images, while also retaining the functional nature of the reconstructed property values. In the present work, we extend the use of prior structural information in microwave imaging from 2D to 3D. This extra dimension adds a significant layer of complexity to the entire image reconstruction procedure. In this paper, several challenges with respect to the 3D microwave imaging will be discussed and the results of a series of 3D simulation and phantom experiments with prior structural information will be studied.

  15. Image Reconstruction Using Analysis Model Prior.

    PubMed

    Han, Yu; Du, Huiqian; Lam, Fan; Mei, Wenbo; Fang, Liping

    2016-01-01

    The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims. PMID:27379171

  16. Image Reconstruction Using Analysis Model Prior

    PubMed Central

    Han, Yu; Du, Huiqian; Lam, Fan; Mei, Wenbo; Fang, Liping

    2016-01-01

    The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims. PMID:27379171

  17. Segmentation of cerebral MRI scans using a partial volume model, shading correction, and an anatomical prior

    NASA Astrophysics Data System (ADS)

    Noe, Aljaz; Kovacic, Stanislav; Gee, James C.

    2001-07-01

    A mixture-model clustering algorithm is presented for robust MRI brain image segmentation in the presence of partial volume averaging. The method uses additional classes to represent partial volume voxels of mixed tissue type in the image. Probability distributions for partial volume voxels are modeled accordingly. The image model also allows for tissue-dependent variance values and voxel neighborhood information is taken into account in the clustering formulation. Additionally we extend the image model to account for a low frequency intensity inhomogeneity that may be present in an image. This so-called shading effect is modeled as a linear combination of polynomial basis functions, and is estimated within the clustering algorithm. We also investigate the possibility of using additional anatomical prior information obtained by registering tissue class template images to the image to be segmented. The final result is the estimated fractional amount of each tissue type present within a voxel in addition to the label assigned to the voxel. A parallel implementation of the method is evaluated using synthetic and real MRI data.

  18. New tissue priors for improved automated classification of subcortical brain structures on MRI.

    PubMed

    Lorio, S; Fresard, S; Adaszewski, S; Kherif, F; Chowdhury, R; Frackowiak, R S; Ashburner, J; Helms, G; Weiskopf, N; Lutti, A; Draganski, B

    2016-04-15

    Despite the constant improvement of algorithms for automated brain tissue classification, the accurate delineation of subcortical structures using magnetic resonance images (MRI) data remains challenging. The main difficulties arise from the low gray-white matter contrast of iron rich areas in T1-weighted (T1w) MRI data and from the lack of adequate priors for basal ganglia and thalamus. The most recent attempts to obtain such priors were based on cohorts with limited size that included subjects in a narrow age range, failing to account for age-related gray-white matter contrast changes. Aiming to improve the anatomical plausibility of automated brain tissue classification from T1w data, we have created new tissue probability maps for subcortical gray matter regions. Supported by atlas-derived spatial information, raters manually labeled subcortical structures in a cohort of healthy subjects using magnetization transfer saturation and R2* MRI maps, which feature optimal gray-white matter contrast in these areas. After assessment of inter-rater variability, the new tissue priors were tested on T1w data within the framework of voxel-based morphometry. The automated detection of gray matter in subcortical areas with our new probability maps was more anatomically plausible compared to the one derived with currently available priors. We provide evidence that the improved delineation compensates age-related bias in the segmentation of iron rich subcortical regions. The new tissue priors, allowing robust detection of basal ganglia and thalamus, have the potential to enhance the sensitivity of voxel-based morphometry in both healthy and diseased brains. PMID:26854557

  19. Prior image constrained image reconstruction in emerging computed tomography applications

    NASA Astrophysics Data System (ADS)

    Brunner, Stephen T.

    Advances have been made in computed tomography (CT), especially in the past five years, by incorporating prior images into the image reconstruction process. In this dissertation, we investigate prior image constrained image reconstruction in three emerging CT applications: dual-energy CT, multi-energy photon-counting CT, and cone-beam CT in image-guided radiation therapy. First, we investigate the application of Prior Image Constrained Compressed Sensing (PICCS) in dual-energy CT, which has been called "one of the hottest research areas in CT." Phantom and animal studies are conducted using a state-of-the-art 64-slice GE Discovery 750 HD CT scanner to investigate the extent to which PICCS can enable radiation dose reduction in material density and virtual monochromatic imaging. Second, we extend the application of PICCS from dual-energy CT to multi-energy photon-counting CT, which has been called "one of the 12 topics in CT to be critical in the next decade." Numerical simulations are conducted to generate multiple energy bin images for a photon-counting CT acquisition and to investigate the extent to which PICCS can enable radiation dose efficiency improvement. Third, we investigate the performance of a newly proposed prior image constrained scatter correction technique to correct scatter-induced shading artifacts in cone-beam CT, which, when used in image-guided radiation therapy procedures, can assist in patient localization, and potentially, dose verification and adaptive radiation therapy. Phantom studies are conducted using a Varian 2100 EX system with an on-board imager to investigate the extent to which the prior image constrained scatter correction technique can mitigate scatter-induced shading artifacts in cone-beam CT. Results show that these prior image constrained image reconstruction techniques can reduce radiation dose in dual-energy CT by 50% in phantom and animal studies in material density and virtual monochromatic imaging, can lead to radiation

  20. TH-A-BRF-11: Image Intensity Non-Uniformities Between MRI Simulation and Diagnostic MRI

    SciTech Connect

    Paulson, E

    2014-06-15

    Purpose: MRI simulation for MRI-based radiotherapy demands that patients be setup in treatment position, which frequently involves use of alternative radiofrequency (RF) coil configurations to accommodate immobilized patients. However, alternative RF coil geometries may exacerbate image intensity non-uniformities (IINU) beyond those observed in diagnostic MRI, which may challenge image segmentation and registration accuracy as well as confound studies assessing radiotherapy response when MR simulation images are used as baselines for evaluation. The goal of this work was to determine whether differences in IINU exist between MR simulation and diagnostic MR images. Methods: ACR-MRI phantom images were acquired at 3T using a spin-echo sequence (TE/TR:20/500ms, rBW:62.5kHz, TH/skip:5/5mm). MR simulation images were obtained by wrapping two flexible phased-array RF coils around the phantom. Diagnostic MR images were obtained by placing the phantom into a commercial phased-array head coil. Pre-scan normalization was enabled in both cases. Images were transferred offline and corrected for IINU using the MNI N3 algorithm. Coefficients of variation (CV=σ/μ) were calculated for each slice. Wilcoxon matched-pairs and Mann-Whitney tests compared CV values between original and N3 images and between MR simulation and diagnostic MR images. Results: Significant differences in CV were detected between original and N3 images in both MRI simulation and diagnostic MRI groups (p=0.010, p=0.010). In addition, significant differences in CV were detected between original MR simulation and original and N3 diagnostic MR images (p=0.0256, p=0.0016). However, no significant differences in CV were detected between N3 MR simulation images and original or N3 diagnostic MR images, demonstrating the importance of correcting MR simulation images beyond pre-scan normalization prior to use in radiotherapy. Conclusions: Alternative RF coil configurations used in MRI simulation can Result in

  1. Color and depth priors in natural images.

    PubMed

    Su, Che-Chun; Cormack, Lawrence K; Bovik, Alan C

    2013-06-01

    Natural scene statistics have played an increasingly important role in both our understanding of the function and evolution of the human vision system, and in the development of modern image processing applications. Because range (egocentric distance) is arguably the most important thing a visual system must compute (from an evolutionary perspective), the joint statistics between image information (color and luminance) and range information are of particular interest. It seems obvious that where there is a depth discontinuity, there must be a higher probability of a brightness or color discontinuity too. This is true, but the more interesting case is in the other direction--because image information is much more easily computed than range information, the key conditional probabilities are those of finding a range discontinuity given an image discontinuity. Here, the intuition is much weaker; the plethora of shadows and textures in the natural environment imply that many image discontinuities must exist without corresponding changes in range. In this paper, we extend previous work in two ways--we use as our starting point a very high quality data set of coregistered color and range values collected specifically for this purpose, and we evaluate the statistics of perceptually relevant chromatic information in addition to luminance, range, and binocular disparity information. The most fundamental finding is that the probabilities of finding range changes do in fact depend in a useful and systematic way on color and luminance changes; larger range changes are associated with larger image changes. Second, we are able to parametrically model the prior marginal and conditional distributions of luminance, color, range, and (computed) binocular disparity. Finally, we provide a proof of principle that this information is useful by showing that our distribution models improve the performance of a Bayesian stereo algorithm on an independent set of input images. To summarize

  2. 4D flow imaging with MRI

    PubMed Central

    Stankovic, Zoran; Allen, Bradley D.; Garcia, Julio; Jarvis, Kelly B.

    2014-01-01

    Magnetic resonance imaging (MRI) has become an important tool for the clinical evaluation of patients with cardiovascular disease. Since its introduction in the late 1980s, 2-dimensional phase contrast MRI (2D PC-MRI) has become a routine part of standard-of-care cardiac MRI for the assessment of regional blood flow in the heart and great vessels. More recently, time-resolved PC-MRI with velocity encoding along all three flow directions and three-dimensional (3D) anatomic coverage (also termed ‘4D flow MRI’) has been developed and applied for the evaluation of cardiovascular hemodynamics in multiple regions of the human body. 4D flow MRI allows for the comprehensive evaluation of complex blood flow patterns by 3D blood flow visualization and flexible retrospective quantification of flow parameters. Recent technical developments, including the utilization of advanced parallel imaging techniques such as k-t GRAPPA, have resulted in reasonable overall scan times, e.g., 8-12 minutes for 4D flow MRI of the aorta and 10-20 minutes for whole heart coverage. As a result, the application of 4D flow MRI in a clinical setting has become more feasible, as documented by an increased number of recent reports on the utility of the technique for the assessment of cardiac and vascular hemodynamics in patient studies. A number of studies have demonstrated the potential of 4D flow MRI to provide an improved assessment of hemodynamics which might aid in the diagnosis and therapeutic management of cardiovascular diseases. The purpose of this review is to describe the methods used for 4D flow MRI acquisition, post-processing and data analysis. In addition, the article provides an overview of the clinical applications of 4D flow MRI and includes a review of applications in the heart, thoracic aorta and hepatic system. PMID:24834414

  3. Microstructural parameter estimation in vivo using diffusion MRI and structured prior information

    PubMed Central

    Nagy, Zoltan; Weiskopf, Nikolaus; Alexander, Daniel C.; Clark, Chris A.

    2015-01-01

    Purpose Diffusion MRI has recently been used with detailed models to probe tissue microstructure. Much of this work has been performed ex vivo with powerful scanner hardware, to gain sensitivity to parameters such as axon radius. By contrast, performing microstructure imaging on clinical scanners is extremely challenging. Methods We use an optimized dual spin‐echo diffusion protocol, and a Bayesian fitting approach, to obtain reproducible contrast (histogram overlap of up to 92%) in estimated maps of axon radius index in healthy adults at a modest, widely‐available gradient strength (35 mT m −1). A key innovation is the use of influential priors. Results We demonstrate that our priors can improve precision in axon radius estimates—a 7‐fold reduction in voxelwise coefficient of variation in vivo—without significant bias. Our results may reflect true axon radius differences between white matter regions, but this interpretation should be treated with caution due to the complexity of the tissue relative to our model. Conclusions Some sensitivity to relatively large axons (3–15 μm) may be available at clinical field and gradient strengths. Future applications at higher gradient strength will benefit from the favorable eddy current properties of the dual spin‐echo sequence, and greater precision available with suitable priors. Magn Reson Med, 2015. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Magn Reson Med 75:1787–1796, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance. PMID:25994918

  4. Developments in boron magnetic resonance imaging (MRI)

    SciTech Connect

    Schweizer, M.

    1995-11-01

    This report summarizes progress during the past year on maturing Boron-11 magnetic resonance imaging (MRI) methodology for noninvasive determination of BNCT agents (BSH) spatially in time. Three major areas are excerpted: (1) Boron-11 MRI of BSH distributions in a canine intracranial tumor model and the first human glioblastoma patient, (2) whole body Boron-11 MRI of BSH pharmacokinetics in a rat flank tumor model, and (3) penetration of gadolinium salts through the BBB as a function of tumor growth in the canine brain.

  5. Investigating the ability of multiparametric MRI to exclude significant prostate cancer prior to transperineal biopsy

    PubMed Central

    Serrao, Eva M.; Barrett, Tristan; Wadhwa, Karan; Parashar, Deepak; Frey, Julia; Koo, Brendan C.; Warren, Anne Y.; Doble, Andrew; Kastner, Christof; Gallagher, Ferdia A.

    2015-01-01

    Introduction: We characterized false negative prostate magnetic resonance imaging (MRI) reporting by using histology derived from MRI-transrectal ultrasound (TRUS)-guided transperineal (MTTP) fusion biopsies. Methods: In total, 148 consecutive patients were retrospectively reviewed. Men underwent multiparametric MRI (mpMRI), reported by a consultant/attending radiologist in line with European Society of Urogenital Radiology (ESUR) standards. MTTP biopsy of the lesions was performed according to the Ginsburg recommendations. Cases with an MRI-histology mismatch were identified and underwent a second read by an experienced radiologist. A third review was performed with direct histology comparison to determine a true miss from an MRI-occult cancer. Statistical analysis was performed with McNemar’s test. Results: False negative lesions were identified in 29 MRI examinations (19.6%), with a total of 46 lesions. Most false negative lesions (21/46) were located in the anterior sectors of the prostate. The second read led to a significant decrease of false-negative lesions with 7/29 further studies identified as positive on a patient-by-patient basis (24.1% of studies, p = 0.016) and 11/46 lesions (23.9%; p = 0.001). Of these, 30 lesions following the first read and 23 lesions after the second read were considered significant cancer according to the University College London criteria. However, on direct comparison with histology, most lesions were MRI occult. Conclusion: We demonstrate that MRI can fail to detect clinically relevant lesions. Improved results were achieved with a second read but despite this, a number of lesions remain MRI-occult. Further advances in imaging are required to reduce false negative results. PMID:26788234

  6. Bayesian symmetrical EEG/fMRI fusion with spatially adaptive priors

    PubMed Central

    Luessi, Martin; Babacan, S. Derin; Molina, Rafael; Booth, James R.; Katsaggelos, Aggelos K.

    2011-01-01

    In this paper, we propose a novel symmetrical EEG/fMRI fusion method which combines EEG and fMRI by means of a common generative model. We use a total variation (TV) prior to model the spatial distribution of the cortical current responses and hemodynamic response functions, and utilize spatially adaptive temporal priors to model their temporal shapes. The spatial adaptivity of the prior model allows for adaptation to the local characteristics of the estimated responses and leads to high estimation performance for the cortical current distribution and the hemodynamic response functions. We utilize a Bayesian formulation with a variational Bayesian framework and obtain a fully automatic fusion algorithm. Simulations with synthetic data and experiments with real data from a multimodal study on face perception demonstrate the performance of the proposed method. PMID:21130173

  7. Hierarchical image segmentation for learning object priors

    SciTech Connect

    Prasad, Lakshman; Yang, Xingwei; Latecki, Longin J; Li, Nan

    2010-11-10

    The proposed segmentation approach naturally combines experience based and image based information. The experience based information is obtained by training a classifier for each object class. For a given test image, the result of each classifier is represented as a probability map. The final segmentation is obtained with a hierarchial image segmentation algorithm that considers both the probability maps and the image features such as color and edge strength. We also utilize image region hierarchy to obtain not only local but also semi-global features as input to the classifiers. Moreover, to get robust probability maps, we take into account the region context information by averaging the probability maps over different levels of the hierarchical segmentation algorithm. The obtained segmentation results are superior to the state-of-the-art supervised image segmentation algorithms.

  8. A fast alignment method for breast MRI follow-up studies using automated breast segmentation and current-prior registration

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Strehlow, Jan; Rühaak, Jan; Weiler, Florian; Diez, Yago; Gubern-Merida, Albert; Diekmann, Susanne; Laue, Hendrik; Hahn, Horst K.

    2015-03-01

    In breast cancer screening for high-risk women, follow-up magnetic resonance images (MRI) are acquired with a time interval ranging from several months up to a few years. Prior MRI studies may provide additional clinical value when examining the current one and thus have the potential to increase sensitivity and specificity of screening. To build a spatial correlation between suspicious findings in both current and prior studies, a reliable alignment method between follow-up studies is desirable. However, long time interval, different scanners and imaging protocols, and varying breast compression can result in a large deformation, which challenges the registration process. In this work, we present a fast and robust spatial alignment framework, which combines automated breast segmentation and current-prior registration techniques in a multi-level fashion. First, fully automatic breast segmentation is applied to extract the breast masks that are used to obtain an initial affine transform. Then, a non-rigid registration algorithm using normalized gradient fields as similarity measure together with curvature regularization is applied. A total of 29 subjects and 58 breast MR images were collected for performance assessment. To evaluate the global registration accuracy, the volume overlap and boundary surface distance metrics are calculated, resulting in an average Dice Similarity Coefficient (DSC) of 0.96 and root mean square distance (RMSD) of 1.64 mm. In addition, to measure local registration accuracy, for each subject a radiologist annotated 10 pairs of markers in the current and prior studies representing corresponding anatomical locations. The average distance error of marker pairs dropped from 67.37 mm to 10.86 mm after applying registration.

  9. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging.

    PubMed

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-04-28

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression.

  10. Measuring glomerular number from kidney MRI images

    NASA Astrophysics Data System (ADS)

    Thiagarajan, Jayaraman J.; Natesan Ramamurthy, Karthikeyan; Kanberoglu, Berkay; Frakes, David; Bennett, Kevin; Spanias, Andreas

    2016-03-01

    Measuring the glomerular number in the entire, intact kidney using non-destructive techniques is of immense importance in studying several renal and systemic diseases. Commonly used approaches either require destruction of the entire kidney or perform extrapolation from measurements obtained from a few isolated sections. A recent magnetic resonance imaging (MRI) method, based on the injection of a contrast agent (cationic ferritin), has been used to effectively identify glomerular regions in the kidney. In this work, we propose a robust, accurate, and low-complexity method for estimating the number of glomeruli from such kidney MRI images. The proposed technique has a training phase and a low-complexity testing phase. In the training phase, organ segmentation is performed on a few expert-marked training images, and glomerular and non-glomerular image patches are extracted. Using non-local sparse coding to compute similarity and dissimilarity graphs between the patches, the subspace in which the glomerular regions can be discriminated from the rest are estimated. For novel test images, the image patches extracted after pre-processing are embedded using the discriminative subspace projections. The testing phase is of low computational complexity since it involves only matrix multiplications, clustering, and simple morphological operations. Preliminary results with MRI data obtained from five kidneys of rats show that the proposed non-invasive, low-complexity approach performs comparably to conventional approaches such as acid maceration and stereology.

  11. Novel Imaging of Prostate Cancer with MRI, MRI/US, and PET.

    PubMed

    Koo, Phillip J; Kwak, Jennifer J; Pokharel, Sajal; Choyke, Peter L

    2015-12-01

    Imaging of prostate cancer presents many challenges to the imaging community. There has been much progress in this space in large part due to MRI and PET radiopharmaceuticals. Though MRI has been focused on the evaluation of local disease and PET on the detection of metastatic disease, these two areas do converge and will be complementary especially with the growth of new PET/MRI technologies. In this review article, we review novel MRI, MRI/US, and PET radiopharmaceuticals which will offer insight into the future direction of imaging in prostate cancer.

  12. Novel Imaging of Prostate Cancer with MRI, MRI/US, and PET.

    PubMed

    Koo, Phillip J; Kwak, Jennifer J; Pokharel, Sajal; Choyke, Peter L

    2015-12-01

    Imaging of prostate cancer presents many challenges to the imaging community. There has been much progress in this space in large part due to MRI and PET radiopharmaceuticals. Though MRI has been focused on the evaluation of local disease and PET on the detection of metastatic disease, these two areas do converge and will be complementary especially with the growth of new PET/MRI technologies. In this review article, we review novel MRI, MRI/US, and PET radiopharmaceuticals which will offer insight into the future direction of imaging in prostate cancer. PMID:26462919

  13. A technique to consider mismatches between fMRI and EEG/MEG sources for fMRI-constrained EEG/MEG source imaging: a preliminary simulation study.

    PubMed

    Im, Chang-Hwan; Lee, Soo Yeol

    2006-12-01

    fMRI-constrained EEG/MEG source imaging can be a powerful tool in studying human brain functions with enhanced spatial and temporal resolutions. Recent studies on the combination of fMRI and EEG/MEG have suggested that fMRI prior information could be readily implemented by simply imposing different weighting factors to cortical sources overlapping with the fMRI activations. It has been also reported, however, that such a hard constraint may cause severe distortions or elimination of meaningful EEG/MEG sources when there are distinct mismatches between the fMRI activations and the EEG/MEG sources. If one wants to obtain the actual EEG/MEG source locations and uses the fMRI prior information as just an auxiliary tool to enhance focality of the distributed EEG/MEG sources, it is reasonable to weaken the strength of fMRI constraint when severe mismatches between fMRI and EEG/MEG sources are observed. The present study suggests an efficient technique to automatically adjust the strength of fMRI constraint according to the mismatch level. The use of the proposed technique rarely affects the results of conventional fMRI-constrained EEG/MEG source imaging if no major mismatch between the two modalities is detected; while the new results become similar to those of typical EEG/MEG source imaging without fMRI constraint if the mismatch level is significant. A preliminary simulation study using realistic EEG signals demonstrated that the proposed technique can be a promising tool to selectively apply fMRI prior information to EEG/MEG source imaging.

  14. Spatial prior in SVM-based classification of brain images

    NASA Astrophysics Data System (ADS)

    Cuingnet, Rémi; Chupin, Marie; Benali, Habib; Colliot, Olivier

    2010-03-01

    This paper introduces a general framework for spatial prior in SVM-based classification of brain images based on Laplacian regularization. Most existing methods include spatial prior by adding a feature aggregation step before the SVM classification. The problem of the aggregation step is that the individual information of each feature is lost. Our framework enables to avoid this shortcoming by including the spatial prior directly in the SVM. We demonstrate that this framework can be used to derive embedded regularization corresponding to existing methods for classification of brain images and propose an efficient way to implement them. This framework is illustrated on the classification of MR images from 55 patients with Alzheimer's disease and 82 elderly controls selected from the ADNI database. The results demonstrate that the proposed algorithm enables introducing straightforward and anatomically consistent spatial prior into the classifier.

  15. A Bayesian Approach for Image Segmentation with Shape Priors

    SciTech Connect

    Chang, Hang; Yang, Qing; Parvin, Bahram

    2008-06-20

    Color and texture have been widely used in image segmentation; however, their performance is often hindered by scene ambiguities, overlapping objects, or missingparts. In this paper, we propose an interactive image segmentation approach with shape prior models within a Bayesian framework. Interactive features, through mouse strokes, reduce ambiguities, and the incorporation of shape priors enhances quality of the segmentation where color and/or texture are not solely adequate. The novelties of our approach are in (i) formulating the segmentation problem in a well-de?ned Bayesian framework with multiple shape priors, (ii) ef?ciently estimating parameters of the Bayesian model, and (iii) multi-object segmentation through user-speci?ed priors. We demonstrate the effectiveness of our method on a set of natural and synthetic images.

  16. Prospective regularization design in prior-image-based reconstruction.

    PubMed

    Dang, Hao; Siewerdsen, Jeffrey H; Stayman, J Webster

    2015-12-21

    Prior-image-based reconstruction (PIBR) methods leveraging patient-specific anatomical information from previous imaging studies and/or sequences have demonstrated dramatic improvements in dose utilization and image quality for low-fidelity data. However, a proper balance of information from the prior images and information from the measurements is required (e.g. through careful tuning of regularization parameters). Inappropriate selection of reconstruction parameters can lead to detrimental effects including false structures and failure to improve image quality. Traditional methods based on heuristics are subject to error and sub-optimal solutions, while exhaustive searches require a large number of computationally intensive image reconstructions. In this work, we propose a novel method that prospectively estimates the optimal amount of prior image information for accurate admission of specific anatomical changes in PIBR without performing full image reconstructions. This method leverages an analytical approximation to the implicitly defined PIBR estimator, and introduces a predictive performance metric leveraging this analytical form and knowledge of a particular presumed anatomical change whose accurate reconstruction is sought. Additionally, since model-based PIBR approaches tend to be space-variant, a spatially varying prior image strength map is proposed to optimally admit changes everywhere in the image (eliminating the need to know change locations a priori). Studies were conducted in both an ellipse phantom and a realistic thorax phantom emulating a lung nodule surveillance scenario. The proposed method demonstrated accurate estimation of the optimal prior image strength while achieving a substantial computational speedup (about a factor of 20) compared to traditional exhaustive search. Moreover, the use of the proposed prior strength map in PIBR demonstrated accurate reconstruction of anatomical changes without foreknowledge of change locations in

  17. Prospective regularization design in prior-image-based reconstruction

    NASA Astrophysics Data System (ADS)

    Dang, Hao; Siewerdsen, Jeffrey H.; Webster Stayman, J.

    2015-12-01

    Prior-image-based reconstruction (PIBR) methods leveraging patient-specific anatomical information from previous imaging studies and/or sequences have demonstrated dramatic improvements in dose utilization and image quality for low-fidelity data. However, a proper balance of information from the prior images and information from the measurements is required (e.g. through careful tuning of regularization parameters). Inappropriate selection of reconstruction parameters can lead to detrimental effects including false structures and failure to improve image quality. Traditional methods based on heuristics are subject to error and sub-optimal solutions, while exhaustive searches require a large number of computationally intensive image reconstructions. In this work, we propose a novel method that prospectively estimates the optimal amount of prior image information for accurate admission of specific anatomical changes in PIBR without performing full image reconstructions. This method leverages an analytical approximation to the implicitly defined PIBR estimator, and introduces a predictive performance metric leveraging this analytical form and knowledge of a particular presumed anatomical change whose accurate reconstruction is sought. Additionally, since model-based PIBR approaches tend to be space-variant, a spatially varying prior image strength map is proposed to optimally admit changes everywhere in the image (eliminating the need to know change locations a priori). Studies were conducted in both an ellipse phantom and a realistic thorax phantom emulating a lung nodule surveillance scenario. The proposed method demonstrated accurate estimation of the optimal prior image strength while achieving a substantial computational speedup (about a factor of 20) compared to traditional exhaustive search. Moreover, the use of the proposed prior strength map in PIBR demonstrated accurate reconstruction of anatomical changes without foreknowledge of change locations in

  18. Statistical shape model-based segmentation of brain MRI images.

    PubMed

    Bailleul, Jonathan; Ruan, Su; Constans, Jean-Marc

    2007-01-01

    We propose a segmentation method that automatically delineates structures contours from 3D brain MRI images using a statistical shape model. We automatically build this 3D Point Distribution Model (PDM) in applying a Minimum Description Length (MDL) annotation to a training set of shapes, obtained by registration of a 3D anatomical atlas over a set of patients brain MRIs. Delineation of any structure from a new MRI image is first initialized by such registration. Then, delineation is achieved in iterating two consecutive steps until the 3D contour reaches idempotence. The first step consists in applying an intensity model to the latest shape position so as to formulate a closer guess: our model requires far less priors than standard model in aiming at direct interpretation rather than compliance to learned contexts. The second step consists in enforcing shape constraints onto previous guess so as to remove all bias induced by artifacts or low contrast on current MRI. For this, we infer the closest shape instance from the PDM shape space using a new estimation method which accuracy is significantly improved by a huge increase in the model resolution and by a depth-search in the parameter space. The delineation results we obtained are very encouraging and show the interest of the proposed framework. PMID:18003193

  19. Target image search using fMRI signals

    NASA Astrophysics Data System (ADS)

    Xiong, Shi; Song, Sutao; Zhan, Yu; Zhang, Jiacai

    2014-03-01

    Recent neural signal decoding studies based on functional magnetic resonance imaging (fMRI) have identified the specific image presenting to the subject from a set of potential images, and some studies extend neural decoding into image reconstruction, i.e. image contents that the subject perceived were decoded from the fMRI signals recorded during the subject looking at images. In this paper, we decoded the target images using fMRI signals and described a target image searching method based on the relationship between target image stimuli and fMRI activity. We recorded fMRI data during a serial visual stimuli image presentation task, some of the stimuli images were target images and the rest images were non-target ones. Our fMRI data analysis results showed that in the serial visual presentation task, target images elicited a stereotypical response in the fMRI, which can be detected by multi-voxel pattern analysis (MVPA). Classifiers designed with support vector machine (SVM) used this response to decipher target images from non-target images. The leave-one-run-out cross-validation showed that we can pick out the target images with a possibility far above the chance level, which indicate that there's a neural signatures correlated with the target image recognition process in the human systems.

  20. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging

    PubMed Central

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression. PMID:27136551

  1. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging.

    PubMed

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression. PMID:27136551

  2. Clinical image: MRI during migraine with aura

    SciTech Connect

    McNeal, A.C.

    1996-03-01

    Migraine refers to severe headaches that are usually unilateral, throbbing, and associated with nausea, vomiting, photophobia, and phonophobia. Migraine with aura (formerly called {open_quotes}classic migraine{close_quotes}) consists of the headache preceded or accompanied by neurological dysfunction. This dysfunction (aura) usually involves visual and sensory symptoms. The patient described herein experienced migraine with aura. MRI during and after the attack showed a reversible abnormality of the right posterior cerebral artery, with no parenchymal lesions. This appears to be the first report of abnormal MR vascular imaging during migraine with aura. 10 refs., 2 figs.

  3. PET image reconstruction with anatomical edge guided level set prior

    NASA Astrophysics Data System (ADS)

    Cheng-Liao, Jinxiu; Qi, Jinyi

    2011-11-01

    Acquiring both anatomical and functional images during one scan, PET/CT systems improve the ability to detect and localize abnormal uptakes. In addition, CT images provide anatomical boundary information that can be used to regularize positron emission tomography (PET) images. Here we propose a new approach to maximum a posteriori reconstruction of PET images with a level set prior guided by anatomical edges. The image prior models both the smoothness of PET images and the similarity between functional boundaries in PET and anatomical boundaries in CT. Level set functions (LSFs) are used to represent smooth and closed functional boundaries. The proposed method does not assume an exact match between PET and CT boundaries. Instead, it encourages similarity between the two boundaries, while allowing different region definition in PET images to accommodate possible signal and position mismatch between functional and anatomical images. While the functional boundaries are guaranteed to be closed by the LSFs, the proposed method does not require closed anatomical boundaries and can utilize incomplete edges obtained from an automatic edge detection algorithm. We conducted computer simulations to evaluate the performance of the proposed method. Two digital phantoms were constructed based on the Digimouse data and a human CT image, respectively. Anatomical edges were extracted automatically from the CT images. Tumors were simulated in the PET phantoms with different mismatched anatomical boundaries. Compared with existing methods, the new method achieved better bias-variance performance. The proposed method was also applied to real mouse data and achieved higher contrast than other methods.

  4. Optimized Bayes variational regularization prior for 3D PET images.

    PubMed

    Rapisarda, Eugenio; Presotto, Luca; De Bernardi, Elisabetta; Gilardi, Maria Carla; Bettinardi, Valentino

    2014-09-01

    A new prior for variational Maximum a Posteriori regularization is proposed to be used in a 3D One-Step-Late (OSL) reconstruction algorithm accounting also for the Point Spread Function (PSF) of the PET system. The new regularization prior strongly smoothes background regions, while preserving transitions. A detectability index is proposed to optimize the prior. The new algorithm has been compared with different reconstruction algorithms such as 3D-OSEM+PSF, 3D-OSEM+PSF+post-filtering and 3D-OSL with a Gauss-Total Variation (GTV) prior. The proposed regularization allows controlling noise, while maintaining good signal recovery; compared to the other algorithms it demonstrates a very good compromise between an improved quantitation and good image quality. PMID:24958594

  5. The Rightful Role of MRI after Negative Conventional Imaging in the Management of Bloody Nipple Discharge.

    PubMed

    Sanders, Linda M; Daigle, Megan

    2016-01-01

    Nipple discharge is a frequent presenting complaint at breast clinics. Bloody nipple discharge (BND) has the highest risk of malignancy, albeit low. If mammogram and ultrasound are unrevealing, central duct excision (CDE) has been considered the gold standard in its management. Magnetic resonance imaging (MRI) has been widely confirmed as a highly sensitive test for detection of breast cancer, with an accompanying high negative predictive value. This article presents a retrospective review of patients with BND and negative conventional imaging, comparing outcome of patients who went directly to CDE without MRI to those patients who underwent preoperative MRI. Of 115 patients who underwent mammography and US alone prior to CDE, eight cancers were detected (seven ductal carcinoma in situ [DCIS] and 1 IDC, 7 mm [T1b]; incidence: 7%). Of 85 patients who underwent conventional imaging followed by MRI prior to surgery, eight cancers were detected (all DCIS; incidence: 9.4%), seven of which were identified by MRI. The one false-negative MRI had subtle findings which, in retrospect, were misinterpreted; however, a clinically apparent nipple lesion prompted surgical biopsy. Of 56 patients with a negative or benign MRI, CDE was negative for malignancy in all but that one patient. Sensitivity and specificity were 87.5%/71.4%. Positive predictive value and negative predictive value (NPV) were 24.1%/98.2%. MRI should be performed in all patients with BND and negative conventional imaging. The extremely high NPV of MRI suggests that a negative study could obviate CDE in most patients unless overriding clinical factors prevail. PMID:26684050

  6. Hemorrhage detection in MRI brain images using images features

    NASA Astrophysics Data System (ADS)

    Moraru, Luminita; Moldovanu, Simona; Bibicu, Dorin; Stratulat (Visan), Mirela

    2013-11-01

    The abnormalities appear frequently on Magnetic Resonance Images (MRI) of brain in elderly patients presenting either stroke or cognitive impairment. Detection of brain hemorrhage lesions in MRI is an important but very time-consuming task. This research aims to develop a method to extract brain tissue features from T2-weighted MR images of the brain using a selection of the most valuable texture features in order to discriminate between normal and affected areas of the brain. Due to textural similarity between normal and affected areas in brain MR images these operation are very challenging. A trauma may cause microstructural changes, which are not necessarily perceptible by visual inspection, but they could be detected by using a texture analysis. The proposed analysis is developed in five steps: i) in the pre-processing step: the de-noising operation is performed using the Daubechies wavelets; ii) the original images were transformed in image features using the first order descriptors; iii) the regions of interest (ROIs) were cropped from images feature following up the axial symmetry properties with respect to the mid - sagittal plan; iv) the variation in the measurement of features was quantified using the two descriptors of the co-occurrence matrix, namely energy and homogeneity; v) finally, the meaningful of the image features is analyzed by using the t-test method. P-value has been applied to the pair of features in order to measure they efficacy.

  7. Heart MRI

    MedlinePlus

    Magnetic resonance imaging - cardiac; Magnetic resonance imaging - heart; Nuclear magnetic resonance - cardiac; NMR - cardiac; MRI of the heart; Cardiomyopathy - MRI; Heart failure - MRI; Congenital heart disease - MRI

  8. Multiresolution segmentation technique for spine MRI images

    NASA Astrophysics Data System (ADS)

    Li, Haiyun; Yan, Chye H.; Ong, Sim Heng; Chui, Cheekong K.; Teoh, Swee H.

    2002-05-01

    In this paper, we describe a hybrid method for segmentation of spinal magnetic resonance imaging that has been developed based on the natural phenomenon of stones appearing as water recedes. The candidate segmentation region corresponds to the stones with characteristics similar to that of intensity extrema, edges, intensity ridge and grey-level blobs. The segmentation method is implemented based on a combination of wavelet multiresolution decomposition and fuzzy clustering. First thresholding is performed dynamically according to local characteristic to detect possible target areas, We then use fuzzy c-means clustering in concert with wavelet multiscale edge detection to identify the maximum likelihood anatomical and functional target areas. Fuzzy C-Means uses iterative optimization of an objective function based on a weighted similarity measure between the pixels in the image and each of c cluster centers. Local extrema of this objective function are indicative of an optimal clustering of the input data. The multiscale edges can be detected and characterized from local maxima of the modulus of the wavelet transform while the noise can be reduced to some extent by enacting thresholds. The method provides an efficient and robust algorithm for spinal image segmentation. Examples are presented to demonstrate the efficiency of the technique on some spinal MRI images.

  9. Improving Bladder Cancer Imaging Using 3T Functional Dynamic Contrast-Enhanced MRI

    PubMed Central

    Nguyen, Huyen T.; Pohar, Kamal S.; Jia, Guang; Shah, Zarine K.; Mortazavi, Amir; Zynger, Debra L.; Wei, Lai; Clark, Daniel; Yang, Xiangyu; Knopp, Michael V.

    2015-01-01

    Objectives To assess the capability of T2-weighted MRI (T2W-MRI) and the additional diagnostic value of Dynamic Contrast-Enhanced MRI (DCE-MRI) using multi-transmit 3T in the localization of bladder cancer. Materials and Methods This prospective study was approved by the local Institutional Review Board. Thirty–six patients were included in the study and provided informed consent. MRI scans were performed with T2W-MRI and DCE-MRI on a 3T multi-transmit system. Two observers (with 12 and 25 years of experience) independently interpreted T2W-MRI prior to DCE-MRI data (maps of pharmacokinetic parameters) to localize bladder tumors. The pathological examination of cystectomy bladder specimens was used as a reference gold standard. The McNemar test was performed to evaluate the differences in sensitivity, specificity, and accuracy. Kappa scores were calculated to assess interobserver agreement. Results The sensitivity, specificity, and accuracy of the localization with T2W-MRI alone were 81% (29/36), 63% (5/8) and 77% (34/44) for observer 1, and 72% (26/36), 63% (5/8), and 70% (31/44) for observer 2. With additional DCE-MRI available, these values were 92% (33/36), 75% (6/8), and 89% (39/44) for observer 1, and 92% (33/36), 63% (5/8), and 86% (38/44) for observer 2. DCE-MRI significantly (P < 0.01) improved the sensitivity and accuracy for observer 2. For the twenty-three patients treated with chemotherapy, DCE-MRI also significantly (P < 0.02) improved the sensitivity and accuracy of bladder cancer localization with T2W-MRI alone for observer 2. Kappa scores were 0.63 for T2W-MRI alone, and 0.78 for additional DCE-MRI. Out of seven sub-centimeter malignant tumors, four (57%) were identified on T2W images and six (86%) on DCE maps. Out of eleven malignant tumors within the bladder wall thickening, six (55%) were found on T2W images and ten (91%) on DCE maps. Conclusions Compared to conventional T2W-MRI alone, the addition of DCE-MRI improved interobserver agreement as

  10. Free Radical Imaging Using In Vivo Dynamic Nuclear Polarization-MRI.

    PubMed

    Utsumi, Hideo; Hyodo, Fuminori

    2015-01-01

    Redox reactions that generate free radical intermediates are essential to metabolic processes, and their intermediates can produce reactive oxygen species, which may promote diseases related to oxidative stress. The development of an in vivo electron spin resonance (ESR) spectrometer and its imaging enables us noninvasive and direct measurement of in vivo free radical reactions in living organisms. The dynamic nuclear polarization magnetic resonance imaging (DNP-MRI), also called PEDRI or OMRI, is also a new imaging method for observing free radical species in vivo. The spatiotemporal resolution of free radical imaging with DNP-MRI is comparable with that in MRI, and each of the radical species can be distinguished in the spectroscopic images by changing the frequency or magnetic field of ESR irradiation. Several kinds of stable nitroxyl radicals were used as spin probes to detect in vivo redox reactions. The signal decay of nitroxyl probes, which is determined with in vivo DNP-MRI, reflects the redox status under oxidative stress, and the signal decay is suppressed by prior administration of antioxidants. In addition, DNP-MRI can also visualize various intermediate free radicals from the intrinsic redox molecules. This noninvasive method, in vivo DNP-MRI, could become a useful tool for investigating the mechanism of oxidative injuries in animal disease models and the in vivo effects of antioxidant drugs.

  11. Current Status of Hybrid PET/MRI in Oncologic Imaging

    PubMed Central

    Rosenkrantz, Andrew B.; Friedman, Kent; Chandarana, Hersh; Melsaether, Amy; Moy, Linda; Ding, Yu-Shin; Jhaveri, Komal; Beltran, Luis; Jain, Rajan

    2016-01-01

    OBJECTIVE This review article explores recent advancements in PET/MRI for clinical oncologic imaging. CONCLUSION Radiologists should understand the technical considerations that have made PET/MRI feasible within clinical workflows, the role of PET tracers for imaging various molecular targets in oncology, and advantages of hybrid PET/MRI compared with PET/CT. To facilitate this understanding, we discuss clinical examples (including gliomas, breast cancer, bone metastases, prostate cancer, bladder cancer, gynecologic malignancy, and lymphoma) as well as future directions, challenges, and areas for continued technical optimization for PET/MRI. PMID:26491894

  12. Prior image constrained compressed sensing: Implementation and performance evaluation

    PubMed Central

    Lauzier, Pascal Thériault; Tang, Jie; Chen, Guang-Hong

    2012-01-01

    Purpose: Prior image constrained compressed sensing (PICCS) is an image reconstruction framework which incorporates an often available prior image into the compressed sensing objective function. The images are reconstructed using an optimization procedure. In this paper, several alternative unconstrained minimization methods are used to implement PICCS. The purpose is to study and compare the performance of each implementation, as well as to evaluate the performance of the PICCS objective function with respect to image quality. Methods: Six different minimization methods are investigated with respect to convergence speed and reconstruction accuracy. These minimization methods include the steepest descent (SD) method and the conjugate gradient (CG) method. These algorithms require a line search to be performed. Thus, for each minimization algorithm, two line searching algorithms are evaluated: a backtracking (BT) line search and a fast Newton-Raphson (NR) line search. The relative root mean square error is used to evaluate the reconstruction accuracy. The algorithm that offers the best convergence speed is used to study the performance of PICCS with respect to the prior image parameter α and the data consistency parameter λ. PICCS is studied in terms of reconstruction accuracy, low-contrast spatial resolution, and noise characteristics. A numerical phantom was simulated and an animal model was scanned using a multirow detector computed tomography (CT) scanner to yield the projection datasets used in this study. Results: For λ within a broad range, the CG method with Fletcher-Reeves formula and NR line search offers the fastest convergence for an equal level of reconstruction accuracy. Using this minimization method, the reconstruction accuracy of PICCS was studied with respect to variations in α and λ. When the number of view angles is varied between 107, 80, 64, 40, 20, and 16, the relative root mean square error reaches a minimum value for α ≈ 0.5. For

  13. Beyond whole-body imaging: advanced imaging techniques of PET/MRI.

    PubMed

    Barnwell, James; Raptis, Constantine A; McConathy, Jonathan E; Laforest, Richard; Siegel, Barry A; Woodard, Pamela K; Fowler, Kathryn

    2015-02-01

    PET/MRI is a hybrid imaging modality that is gaining clinical interest with the first Food and Drug Administration-approved simultaneous imaging system recently added to the clinical armamentarium. Several advanced PET/MRI applications, such as high-resolution anatomic imaging, diffusion-weighted imaging, motion correction, and cardiac imaging, show great potential for clinical use. The purpose of this article is to highlight several advanced PET/MRI applications through case examples and review of the current literature.

  14. fMRI evidence of equivalent neural suppression by repetition and prior knowledge.

    PubMed

    Poppenk, J; McIntosh, A R; Moscovitch, M

    2016-09-01

    Stimulus repetition speeds behavioral responding (behavioral priming) and is accompanied by suppressed neural responses (repetition suppression; RS) that have been observed up to three days after initial exposure. While some proposals have suggested the two phenomena are linked, behavioral priming has been observed many years after initial exposure, whereas RS is widely considered a transitory phenomenon. This raises the question: what is the true upper limit of RS persistence? To answer this question, we scanned healthy, English-native adults with fMRI as they viewed novel (Asian) proverbs, recently repeated (Asian) proverbs, and previously known (English) proverbs that were matched on various dimensions. We then estimated RS by comparing repeated or previously known proverbs against novel ones. Multivariate analyses linked previously known and repeated proverbs with statistically indistinguishable RS in a broad visual-linguistic network. In each suppressed region, prior knowledge and repetition also induced a common shift in functional connectivity, further underscoring the similarity of the RS phenomenon induced by these conditions. By contrast, activated regions readily distinguished prior knowledge and repetition conditions in a manner consistent with engagement of semantic and episodic memory systems, respectively. Our results illustrate that regardless of whether RS is understood in terms of its magnitude, spatial extent or functional connectivity profile, typical RS effects can be elicited even under conditions where recently triggered biological processes or episodic memory are unlikely to play a prominent role. These results provide important new evidence that RS (of the kind observed after an interval of at least several minutes) reflects the facilitation of perceptual and comprehension processes by any type of information retrieved from long-term memory. PMID:27461077

  15. Magnetization transfer prepared gradient echo MRI for CEST imaging.

    PubMed

    Dai, Zhuozhi; Ji, Jim; Xiao, Gang; Yan, Gen; Li, Shengkai; Zhang, Guishan; Lin, Yan; Shen, Zhiwei; Wu, Renhua

    2014-01-01

    Chemical exchange saturation transfer (CEST) is an emerging MRI contrast mechanism that is capable of noninvasively imaging dilute CEST agents and local properties such as pH and temperature, augmenting the routine MRI methods. However, the routine CEST MRI includes a long RF saturation pulse followed by fast image readout, which is associated with high specific absorption rate and limited spatial resolution. In addition, echo planar imaging (EPI)-based fast image readout is prone to image distortion, particularly severe at high field. To address these limitations, we evaluated magnetization transfer (MT) prepared gradient echo (GRE) MRI for CEST imaging. We proved the feasibility using numerical simulations and experiments in vitro and in vivo. Then we optimized the sequence by serially evaluating the effects of the number of saturation steps, MT saturation power (B1), GRE readout flip angle (FA), and repetition time (TR) upon the CEST MRI, and further demonstrated the endogenous amide proton CEST imaging in rats brains (n = 5) that underwent permanent middle cerebral artery occlusion. The CEST images can identify ischemic lesions in the first 3 hours after occlusion. In summary, our study demonstrated that the readily available MT-prepared GRE MRI, if optimized, is CEST-sensitive and remains promising for translational CEST imaging. PMID:25384020

  16. PET/MRI in Oncological Imaging: State of the Art

    PubMed Central

    Bashir, Usman; Mallia, Andrew; Stirling, James; Joemon, John; MacKewn, Jane; Charles-Edwards, Geoff; Goh, Vicky; Cook, Gary J.

    2015-01-01

    Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition sequences. Several studies have shown PET/MRI to be equivalent to PET/CT in most oncological applications, possibly superior in certain body parts, e.g., head and neck, pelvis, and in certain situations, e.g., cancer recurrence. This review will update the readers on recent advances in PET/MRI technology and review key literature, while highlighting the strengths and weaknesses of PET/MRI in cancer imaging. PMID:26854157

  17. PET/MRI in Oncological Imaging: State of the Art.

    PubMed

    Bashir, Usman; Mallia, Andrew; Stirling, James; Joemon, John; MacKewn, Jane; Charles-Edwards, Geoff; Goh, Vicky; Cook, Gary J

    2015-01-01

    Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition sequences. Several studies have shown PET/MRI to be equivalent to PET/CT in most oncological applications, possibly superior in certain body parts, e.g., head and neck, pelvis, and in certain situations, e.g., cancer recurrence. This review will update the readers on recent advances in PET/MRI technology and review key literature, while highlighting the strengths and weaknesses of PET/MRI in cancer imaging. PMID:26854157

  18. MRI-coupled spectrally-resolved fluorescence tomography for in vivo imaging

    NASA Astrophysics Data System (ADS)

    Davis, Scott C.; Gibbs-Strauss, Summer L.; Tuttle, Stephen B.; Jiang, Shudong; Springett, Roger; Dehghani, Hamid; Pogue, Brian W.; Paulsen, Keith D.

    2008-02-01

    A unique fluorescence imaging system incorporates multi-channel spectrometer-based optical detection directly into clinical MRI for simultaneous MR and spectrally-resolved fluorescence tomography acquisition in small animal and human breast-sized volumes. A custom designed MRI rodent coil adapted to accommodate optical fibers in a circular geometry for contact mode acquisition provides small animal imaging capabilities, and human breast-sized volumes are imaged using a clinical breast coil modified with an optical fiber patient array. Spectroscopy fibers couple light emitted from the tissue surface to sixteen highly sensitive CCD-based spectrometers operating in parallel. Tissue structural information obtained from standard and contrast enhanced T1-weighted images is used to spatially constrain the diffuse fluorescence tomography reconstruction algorithm, improving fluorescence imaging capabilities qualitatively and quantitatively. Simultaneous acquisition precludes the use of complex co-registration processes. Calibration procedures for the optical acquisition system are reviewed and the imaging limits of the system are investigated in homogeneous and heterogeneous gelatin phantoms containing Indocyanine Green (ICG). Prior knowledge of fluorescence emission spectra is used to de-couple fluorescence emission from residual excitation laser cross-talk. Preliminary in vivo data suggests improved fluorescence imaging in mouse brain tumors using MR-derived spatial priors. U-251 human gliomas were implanted intracranially into nude mice and combined contrast enhanced MRI/fluorescence tomography acquisition was completed at 24 hour intervals over the course of 72 hours after administration of an EGFR targeted NIR fluorophore. Reconstructed images demonstrate an inability to recover reasonable images of fluorescence activity without the use of MRI spatial priors.

  19. Imaging transplanted stem cells in real time using an MRI dual-contrast method

    PubMed Central

    Ngen, Ethel J.; Wang, Lee; Kato, Yoshinori; Krishnamachary, Balaji; Zhu, Wenlian; Gandhi, Nishant; Smith, Barbara; Armour, Michael; Wong, John; Gabrielson, Kathleen; Artemov, Dmitri

    2015-01-01

    Stem cell therapies are currently being investigated for the repair of brain injuries. Although exogenous stem cell labelling with superparamagnetic iron oxide nanoparticles (SPIONs) prior to transplantation provides a means to noninvasively monitor stem cell transplantation by magnetic resonance imaging (MRI), monitoring cell death is still a challenge. Here, we investigate the feasibility of using an MRI dual-contrast technique to detect cell delivery, cell migration and cell death after stem cell transplantation. Human mesenchymal stem cells were dual labelled with SPIONs and gadolinium-based chelates (GdDTPA). The viability, proliferation rate, and differentiation potential of the labelled cells were then evaluated. The feasibility of this MRI technique to distinguish between live and dead cells was next evaluated using MRI phantoms, and in vivo using both immune-competent and immune-deficient mice, following the induction of brain injury in the mice. All results were validated with bioluminescence imaging. In live cells, a negative (T2/T2*) MRI contrast predominates, and is used to track cell delivery and cell migration. Upon cell death, a diffused positive (T1) MRI contrast is generated in the vicinity of the dead cells, and serves as an imaging marker for cell death. Ultimately, this technique could be used to manage stem cell therapies. PMID:26330231

  20. Imaging transplanted stem cells in real time using an MRI dual-contrast method.

    PubMed

    Ngen, Ethel J; Wang, Lee; Kato, Yoshinori; Krishnamachary, Balaji; Zhu, Wenlian; Gandhi, Nishant; Smith, Barbara; Armour, Michael; Wong, John; Gabrielson, Kathleen; Artemov, Dmitri

    2015-09-02

    Stem cell therapies are currently being investigated for the repair of brain injuries. Although exogenous stem cell labelling with superparamagnetic iron oxide nanoparticles (SPIONs) prior to transplantation provides a means to noninvasively monitor stem cell transplantation by magnetic resonance imaging (MRI), monitoring cell death is still a challenge. Here, we investigate the feasibility of using an MRI dual-contrast technique to detect cell delivery, cell migration and cell death after stem cell transplantation. Human mesenchymal stem cells were dual labelled with SPIONs and gadolinium-based chelates (GdDTPA). The viability, proliferation rate, and differentiation potential of the labelled cells were then evaluated. The feasibility of this MRI technique to distinguish between live and dead cells was next evaluated using MRI phantoms, and in vivo using both immune-competent and immune-deficient mice, following the induction of brain injury in the mice. All results were validated with bioluminescence imaging. In live cells, a negative (T2/T2*) MRI contrast predominates, and is used to track cell delivery and cell migration. Upon cell death, a diffused positive (T1) MRI contrast is generated in the vicinity of the dead cells, and serves as an imaging marker for cell death. Ultimately, this technique could be used to manage stem cell therapies.

  1. [MRI of the prostate: optimization of imaging protocols].

    PubMed

    Rouvière, O

    2006-02-01

    This article details the imaging protocols for prostate MRI and the influence on image quality of each particular setting: type of coils to be used (endorectal or external phased-array coils?), patient preparation, type of sequences, spatial resolution parameters. The principle and technical constraints of dynamic contrast-enhanced MRI are also presented, as well as the predictable changes due to the introduction of high-field strength (3T) scanners.

  2. Registration of 2D x-ray images to 3D MRI by generating pseudo-CT data

    NASA Astrophysics Data System (ADS)

    van der Bom, M. J.; Pluim, J. P. W.; Gounis, M. J.; van de Kraats, E. B.; Sprinkhuizen, S. M.; Timmer, J.; Homan, R.; Bartels, L. W.

    2011-02-01

    Spatial and soft tissue information provided by magnetic resonance imaging can be very valuable during image-guided procedures, where usually only real-time two-dimensional (2D) x-ray images are available. Registration of 2D x-ray images to three-dimensional (3D) magnetic resonance imaging (MRI) data, acquired prior to the procedure, can provide optimal information to guide the procedure. However, registering x-ray images to MRI data is not a trivial task because of their fundamental difference in tissue contrast. This paper presents a technique that generates pseudo-computed tomography (CT) data from multi-spectral MRI acquisitions which is sufficiently similar to real CT data to enable registration of x-ray to MRI with comparable accuracy as registration of x-ray to CT. The method is based on a k-nearest-neighbors (kNN)-regression strategy which labels voxels of MRI data with CT Hounsfield Units. The regression method uses multi-spectral MRI intensities and intensity gradients as features to discriminate between various tissue types. The efficacy of using pseudo-CT data for registration of x-ray to MRI was tested on ex vivo animal data. 2D-3D registration experiments using CT and pseudo-CT data of multiple subjects were performed with a commonly used 2D-3D registration algorithm. On average, the median target registration error for registration of two x-ray images to MRI data was approximately 1 mm larger than for x-ray to CT registration. The authors have shown that pseudo-CT data generated from multi-spectral MRI facilitate registration of MRI to x-ray images. From the experiments it could be concluded that the accuracy achieved was comparable to that of registering x-ray images to CT data.

  3. Prior image constrained scatter correction in cone-beam computed tomography image-guided radiation therapy

    NASA Astrophysics Data System (ADS)

    Brunner, Stephen; Nett, Brian E.; Tolakanahalli, Ranjini; Chen, Guang-Hong

    2011-02-01

    X-ray scatter is a significant problem in cone-beam computed tomography when thicker objects and larger cone angles are used, as scattered radiation can lead to reduced contrast and CT number inaccuracy. Advances have been made in x-ray computed tomography (CT) by incorporating a high quality prior image into the image reconstruction process. In this paper, we extend this idea to correct scatter-induced shading artifacts in cone-beam CT image-guided radiation therapy. Specifically, this paper presents a new scatter correction algorithm which uses a prior image with low scatter artifacts to reduce shading artifacts in cone-beam CT images acquired under conditions of high scatter. The proposed correction algorithm begins with an empirical hypothesis that the target image can be written as a weighted summation of a series of basis images that are generated by raising the raw cone-beam projection data to different powers, and then, reconstructing using the standard filtered backprojection algorithm. The weight for each basis image is calculated by minimizing the difference between the target image and the prior image. The performance of the scatter correction algorithm is qualitatively and quantitatively evaluated through phantom studies using a Varian 2100 EX System with an on-board imager. Results show that the proposed scatter correction algorithm using a prior image with low scatter artifacts can substantially mitigate scatter-induced shading artifacts in both full-fan and half-fan modes.

  4. Multi-modal image registration: matching MRI with histology

    NASA Astrophysics Data System (ADS)

    Alic, Lejla; Haeck, Joost C.; Klein, Stefan; Bol, Karin; van Tiel, Sandra T.; Wielopolski, Piotr A.; Bijster, Magda; Niessen, Wiro J.; Bernsen, Monique; Veenland, Jifke F.; de Jong, Marion

    2010-03-01

    Spatial correspondence between histology and multi sequence MRI can provide information about the capabilities of non-invasive imaging to characterize cancerous tissue. However, shrinkage and deformation occurring during the excision of the tumor and the histological processing complicate the co registration of MR images with histological sections. This work proposes a methodology to establish a detailed 3D relation between histology sections and in vivo MRI tumor data. The key features of the methodology are a very dense histological sampling (up to 100 histology slices per tumor), mutual information based non-rigid B-spline registration, the utilization of the whole 3D data sets, and the exploitation of an intermediate ex vivo MRI. In this proof of concept paper, the methodology was applied to one tumor. We found that, after registration, the visual alignment of tumor borders and internal structures was fairly accurate. Utilizing the intermediate ex vivo MRI, it was possible to account for changes caused by the excision of the tumor: we observed a tumor expansion of 20%. Also the effects of fixation, dehydration and histological sectioning could be determined: 26% shrinkage of the tumor was found. The annotation of viable tissue, performed in histology and transformed to the in vivo MRI, matched clearly with high intensity regions in MRI. With this methodology, histological annotation can be directly related to the corresponding in vivo MRI. This is a vital step for the evaluation of the feasibility of multi-spectral MRI to depict histological groundtruth.

  5. Ultrasound vs. MRI in the assessment of rotator cuff structure prior to shoulder arthroplasty

    PubMed Central

    Fischer, Christian Alexander; Weber, Marc-André; Neubecker, Clément; Bruckner, Thomas; Tanner, Michael; Zeifang, Felix

    2015-01-01

    Background/Aims We compared the accuracy of US to 3 T Tesla MRI for the detection of rotator cuff and long biceps tendon pathologies before joint replacement. Methods 45 patients were prospectively included. Results For the supraspinatus tendon, the accuracy of US when using MRI as reference was 91.1%. For the infraspinatus tendon, the accuracy with MRI as reference was 84.4%. The subscapularis tendon was consistently assessed by US and MRI in 35/45 patients (accuracy 77.8%). For the long biceps tendon the accuracy was 86.7%. Conclusion US detection of rotator cuff and biceps tendon integrity is comparable to MRI and should be preferred in revision cases. PMID:25829757

  6. Prostate cancer magnetic resonance imaging (MRI): multidisciplinary standpoint

    PubMed Central

    Li, Liang; Feng, Zhaoyan; Hu, Zhiquan; Wang, Guoping; Yuan, Xianglin; Wang, He; Hu, Daoyu

    2013-01-01

    Prostate cancer is the most common cancer diagnosed in men and a leading cause of death. Accurate assessment is a prerequisite for optimal clinical management and therapy selection of prostate cancer. There are several parameters and nomograms to differentiate between patients with clinically insignificant disease and patients in need of treatment. Magnetic resonance imaging (MRI) is a technique which provides more detailed anatomical images due to high spatial resolution, superior contrast resolution, and multiplanar capability. State-of-the-art MRI techniques, such as diffusion weighted imaging (DWI), MR spectroscopic imaging (MRSI), dynamic contrast enhanced MRI (DCE-MRI), improve interpretation of prostate cancer imaging. In this article, we review the major role of MRI in the advanced management of prostate cancer to noninvasively improve tumor staging, biologic potential, treatment planning, therapy response, local recurrence, and to guide target biopsy for clinical suspected cancer with previous negative biopsy. Finally, future challenges and opportunities in prostate cancer management in the area of functional MRI are discussed as well. PMID:23630657

  7. Fusion of PET and MRI for Hybrid Imaging

    NASA Astrophysics Data System (ADS)

    Cho, Zang-Hee; Son, Young-Don; Kim, Young-Bo; Yoo, Seung-Schik

    Recently, the development of the fusion PET-MRI system has been actively studied to meet the increasing demand for integrated molecular and anatomical imaging. MRI can provide detailed anatomical information on the brain, such as the locations of gray and white matter, blood vessels, axonal tracts with high resolution, while PET can measure molecular and genetic information, such as glucose metabolism, neurotransmitter-neuroreceptor binding and affinity, protein-protein interactions, and gene trafficking among biological tissues. State-of-the-art MRI systems, such as the 7.0 T whole-body MRI, now can visualize super-fine structures including neuronal bundles in the pons, fine blood vessels (such as lenticulostriate arteries) without invasive contrast agents, in vivo hippocampal substructures, and substantia nigra with excellent image contrast. High-resolution PET, known as High-Resolution Research Tomograph (HRRT), is a brain-dedicated system capable of imaging minute changes of chemicals, such as neurotransmitters and -receptors, with high spatial resolution and sensitivity. The synergistic power of the two, i.e., ultra high-resolution anatomical information offered by a 7.0 T MRI system combined with the high-sensitivity molecular information offered by HRRT-PET, will significantly elevate the level of our current understanding of the human brain, one of the most delicate, complex, and mysterious biological organs. This chapter introduces MRI, PET, and PET-MRI fusion system, and its algorithms are discussed in detail.

  8. Update of diagnostic preoperative images using low-field interventional MRI for navigation in neurosurgery: rigid-body registration

    NASA Astrophysics Data System (ADS)

    Kavec, Martin; Wikler, David; Phillips, Christophe L. M.; Vigneron, Lara M.; Levivier, Marc; Verly, Jacques G.

    2005-04-01

    This study looks into the rigid-body registration of pre-operative anatomical high field and interventional low field magnetic resonance images (MRI). The accurate 3D registration of these modalities is required to enhance the content of interventional images with anatomical (CT, high field MRI, DTI), functional (DWI, fMRI, PWI), metabolic (PET) or angiography (CTA, MRA) pre-operative images. The specific design of the interventional MRI scanner used in the present study, a PoleStar N20, induces image artifacts, such as ellipsoidal masking and intensity inhomogeneities, which affect registration performance. On MRI data from eleven patients, who underwent resection of a brain tumor, we quantitatively evaluated the effects of artifacts in the image registration process based on a normalized mutual information (NMI) metric criterion. The results show that the quality of alignment of pre-operative anatomical and interventional images strongly depends on pre-processing carried out prior to registration. The registration results scored the highest in visual evaluation only if intensity variations and masking were considered in image registration. We conclude that the alignment of anatomical high field MRI and PoleStar interventional images is the most accurate when the PoleStar's induced image artifacts are corrected for before registration.

  9. Imaging and 3-D dosimetry: top tips for MRI and optical CT

    NASA Astrophysics Data System (ADS)

    Doran, Simon J.

    2010-11-01

    The conference "refresher session" associated with this abstract reviews the main principles of the two most important imaging readout modalities for 3-D dosimetry: MRI and optical CT. Best practices for both these techniques are already described in several different places in the literature, but, for the uninitiated, there are a number of pitfalls. Here, I list some of the important considerations required to obtain good results from these methods and point to relevant prior work.

  10. A novel right ventricle segmentation strategy using local spatio-temporal MRI information with a prior regularizer term

    NASA Astrophysics Data System (ADS)

    Atehortúa, Angélica; Martínez, Fabio; Romero, Eduardo

    2013-11-01

    In this work is presented a novel strategy that tracks the right ventricle (RV) shape during a whole cardiac cycle in magnetic resonance sequences (MRC). The proposed approach obtains a set of spatio-temporal observations from a bidirectional per pixel motion descriptor which are each time fused with prior learned edges. A main advantage of the proposed approach is a robust MRI heart characterization that is regularized by a prior information, obtaining in each cardiac state coherent results. The proposed approach achieves a Dice Score of 0.64 evaluated over 16 patients.

  11. WE-G-18A-05: Cone-Beam CT Reconstruction with Deformed Prior Image

    SciTech Connect

    Zhang, H; Huang, J; Ma, J; Chen, W; Ouyang, L; Wang, J

    2014-06-15

    Purpose: Prior image can be incorporated into image reconstruction process to improve the quality of on-treatment cone-beam CT (CBCT) from sparseview or low-dose projections. However, the deformation between the prior image and on-treatment CBCT are not considered in current prior image based reconstructions (e.g., prior image constrained compressed sensing (PICCS)). The purpose of this work is to develop a deformed-prior-imagebased- reconstruction strategy (DPIR) to address the mismatch problem between the prior image and target image. Methods: The deformed prior image is obtained by a projection based registration approach. Specifically, the deformation vector fields (DVF) used to deform the prior image is estimated through matching the forward projection of the prior image and the measured on-treatment projection. The deformed prior image is then used as the prior image in the standard PICCS algorithm. Simulation studies on the XCAT phantom was conducted to evaluate the performance of the projection based registration procedure and the proposed DPIR strategy. Results: The deformed prior image matches the geometry of on-treatment CBCT closer as compared to the original prior image. Using the deformed prior image, the quality of the image reconstructed by DPIR from few-view projection data is greatly improved as compared to the standard PICCS algorithm. The relative image reconstruction error is reduced to 11.13% in the proposed DPIR from 17.57% in the original PICCS. Conclusion: The proposed DPIR approach can solve the mismatch problem between the prior image and target image, which overcomes the limitation of the original PICCS algorithm for CBCT reconstruction from sparse-view or low-dose projections.

  12. Motion Compensated Abdominal Diffusion Weighted MRI by Simultaneous Image Registration and Model Estimation (SIR-ME).

    PubMed

    Kurugol, Sila; Freiman, Moti; Afacan, Onur; Domachevsky, Liran; Perez-Rossello, Jeannette M; Callahan, Michael J; Warfield, Simon K

    2015-01-01

    Non-invasive characterization of water molecule's mobility variations by quantitative analysis of diffusion-weighted MRI (DW-MRI) signal decay in the abdomen has the potential to serve as a biomarker in gastrointestinal and oncological applications. Accurate and reproducible estimation of the signal decay model parameters is challenging due to the presence of respiratory, cardiac, and peristalsis motion. Independent registration of each b-value image to the b-value=0 s/mm(2) image prior to parameter estimation might be sub-optimal because of the low SNR and contrast difference between images of varying b-value. In this work, we introduce a motion-compensated parameter estimation framework that simultaneously solves image registration and model estimation (SIR-ME) problems by utilizing the interdependence of acquired volumes along the diffusion weighting dimension. We evaluated the improvement in model parameters estimation accuracy using 16 in-vivo DW-MRI data sets of Crohn's disease patients by comparing parameter estimates obtained using the SIR-ME model to the parameter estimates obtained by fitting the signal decay model to the acquired DW-MRI images. The proposed SIR-ME model reduced the average root-mean-square error between the observed signal and the fitted model by more than 50%. Moreover, the SIR-ME model estimates discriminate between normal and abnormal bowel loops better than the standard parameter estimates.

  13. Imaging of the aortic valve with MRI and CT angiography.

    PubMed

    Harvey, J J; Hoey, E T D; Ganeshan, A

    2013-12-01

    The aortic valve may be affected by a wide range of congenital and acquired diseases. Echocardiography is the main non-invasive imaging technique for assessing patho-anatomical alterations of the aortic valve and adjacent structures and in many cases is sufficient to establish a diagnosis and/or guide treatment decisions. Recent technological advances in magnetic resonance imaging (MRI) and multidetector computed tomography (MDCT) have enabled these techniques to play a complimentary role in certain clinical scenarios and as such can be useful problem-solving tools. Radiologists should be familiar with the indications, advantages, and limitations of MRI and MDCT in order to advise and direct an appropriate imaging strategy depending upon the clinical scenario. This article reviews the role of MRI and MDCT angiography for assessment of the aortic valve including relevant anatomy, scan acquisition protocols, and post-processing methods. An approach to interpretation and the key imaging features of commonly encountered aortic valvular diseases are discussed.

  14. Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET)/MRI for Lung Cancer Staging.

    PubMed

    Ohno, Yoshiharu; Koyama, Hisanobu; Lee, Ho Yun; Yoshikawa, Takeshi; Sugimura, Kazuro

    2016-07-01

    Tumor, lymph node, and metastasis (TNM) classification of lung cancer is typically performed with the TNM staging system, as recommended by the Union Internationale Contre le Cancer (UICC), the American Joint Committee on Cancer (AJCC), and the International Association for the Study of Lung Cancer (IASLC). Radiologic examinations for TNM staging of lung cancer patients include computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG-PET), and FDG-PET combined with CT (FDG-PET/CT) and are used for pretherapeutic assessments. Recent technical advances in MR systems, application of fast and parallel imaging and/or introduction of new MR techniques, and utilization of contrast media have markedly improved the diagnostic utility of MRI in this setting. In addition, FDG-PET can be combined or fused with MRI (PET/MRI) for clinical practice. This review article will focus on these recent advances in MRI as well as on PET/MRI for lung cancer staging, in addition to a discussion of their potential and limitations for routine clinical practice in comparison with other modalities such as CT, FDG-PET, and PET/CT.

  15. Micro-imaging of the Mouse Lung via MRI

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    inflammation, particularly in the lung periphery, indicating airspace enlargement after virus infection. Another important application of the imaging technique is the study of lung regeneration in a pneumonectomy (PNX) model. Partial resection of the lung by unilateral PNX is a robust model of compensatory lung growth. It is typically studied by postmortem morphometry in which longitudinal assessment in the same animal cannot be achieved. Here we successfully assess the microstructural changes and quantify the compensatory lung growth in vivo in the PNX mouse model via 1H and hyperpolarized 3He diffusion MRI. Our results show complete restoration in lung volume and total alveolar number with enlargement of alveolar size, which is consistent with prior histological studies conducted in different animals at various time points. This dissertation demonstrates that 3He lung morphometry has good sensitivity in quantifying small microstructural changes in the mouse lung and can be applied to a variety of mouse pulmonary models. Particularly, it has great potential to become a valuable tool in understanding the time course and the mechanism of lung growth in individual animals and may provide insight into post-natal lung growth and lung regeneration.

  16. PCA-based groupwise image registration for quantitative MRI.

    PubMed

    Huizinga, W; Poot, D H J; Guyader, J-M; Klaassen, R; Coolen, B F; van Kranenburg, M; van Geuns, R J M; Uitterdijk, A; Polfliet, M; Vandemeulebroucke, J; Leemans, A; Niessen, W J; Klein, S

    2016-04-01

    Quantitative magnetic resonance imaging (qMRI) is a technique for estimating quantitative tissue properties, such as the T1 and T2 relaxation times, apparent diffusion coefficient (ADC), and various perfusion measures. This estimation is achieved by acquiring multiple images with different acquisition parameters (or at multiple time points after injection of a contrast agent) and by fitting a qMRI signal model to the image intensities. Image registration is often necessary to compensate for misalignments due to subject motion and/or geometric distortions caused by the acquisition. However, large differences in image appearance make accurate image registration challenging. In this work, we propose a groupwise image registration method for compensating misalignment in qMRI. The groupwise formulation of the method eliminates the requirement of choosing a reference image, thus avoiding a registration bias. The method minimizes a cost function that is based on principal component analysis (PCA), exploiting the fact that intensity changes in qMRI can be described by a low-dimensional signal model, but not requiring knowledge on the specific acquisition model. The method was evaluated on 4D CT data of the lungs, and both real and synthetic images of five different qMRI applications: T1 mapping in a porcine heart, combined T1 and T2 mapping in carotid arteries, ADC mapping in the abdomen, diffusion tensor mapping in the brain, and dynamic contrast-enhanced mapping in the abdomen. Each application is based on a different acquisition model. The method is compared to a mutual information-based pairwise registration method and four other state-of-the-art groupwise registration methods. Registration accuracy is evaluated in terms of the precision of the estimated qMRI parameters, overlap of segmented structures, distance between corresponding landmarks, and smoothness of the deformation. In all qMRI applications the proposed method performed better than or equally well as

  17. PCA-based groupwise image registration for quantitative MRI.

    PubMed

    Huizinga, W; Poot, D H J; Guyader, J-M; Klaassen, R; Coolen, B F; van Kranenburg, M; van Geuns, R J M; Uitterdijk, A; Polfliet, M; Vandemeulebroucke, J; Leemans, A; Niessen, W J; Klein, S

    2016-04-01

    Quantitative magnetic resonance imaging (qMRI) is a technique for estimating quantitative tissue properties, such as the T1 and T2 relaxation times, apparent diffusion coefficient (ADC), and various perfusion measures. This estimation is achieved by acquiring multiple images with different acquisition parameters (or at multiple time points after injection of a contrast agent) and by fitting a qMRI signal model to the image intensities. Image registration is often necessary to compensate for misalignments due to subject motion and/or geometric distortions caused by the acquisition. However, large differences in image appearance make accurate image registration challenging. In this work, we propose a groupwise image registration method for compensating misalignment in qMRI. The groupwise formulation of the method eliminates the requirement of choosing a reference image, thus avoiding a registration bias. The method minimizes a cost function that is based on principal component analysis (PCA), exploiting the fact that intensity changes in qMRI can be described by a low-dimensional signal model, but not requiring knowledge on the specific acquisition model. The method was evaluated on 4D CT data of the lungs, and both real and synthetic images of five different qMRI applications: T1 mapping in a porcine heart, combined T1 and T2 mapping in carotid arteries, ADC mapping in the abdomen, diffusion tensor mapping in the brain, and dynamic contrast-enhanced mapping in the abdomen. Each application is based on a different acquisition model. The method is compared to a mutual information-based pairwise registration method and four other state-of-the-art groupwise registration methods. Registration accuracy is evaluated in terms of the precision of the estimated qMRI parameters, overlap of segmented structures, distance between corresponding landmarks, and smoothness of the deformation. In all qMRI applications the proposed method performed better than or equally well as

  18. Comparison of functional MRI image realignment tools using a computer-generated phantom.

    PubMed

    Morgan, V L; Pickens, D R; Hartmann, S L; Price, R R

    2001-09-01

    This study discusses the development of a computer-generated phantom to compare the effects of image realignment programs on functional MRI (fMRI) pixel activation. The phantom is a whole-head MRI volume with added random noise, activation, and motion. It allows simulation of realistic head motions with controlled areas of activation. Without motion, the phantom shows the effects of realignment on motion-free data sets. Prior to realignment, the phantom illustrates some activation corruption due to motion. Finally, three widely used realignment packages are examined. The results showed that the most accurate algorithms are able to increase specificity through accurate realignment while maintaining sensitivity through effective resampling techniques. In fact, accurate realignment alone is not a powerful indicator of the most effective algorithm in terms of true activation.

  19. Atlas-registration based image segmentation of MRI human thigh muscles in 3D space

    NASA Astrophysics Data System (ADS)

    Ahmad, Ezak; Yap, Moi Hoon; Degens, Hans; McPhee, Jamie S.

    2014-03-01

    Automatic segmentation of anatomic structures of magnetic resonance thigh scans can be a challenging task due to the potential lack of precisely defined muscle boundaries and issues related to intensity inhomogeneity or bias field across an image. In this paper, we demonstrate a combination framework of atlas construction and image registration methods to propagate the desired region of interest (ROI) between atlas image and the targeted MRI thigh scans for quadriceps muscles, femur cortical layer and bone marrow segmentations. The proposed system employs a semi-automatic segmentation method on an initial image in one dataset (from a series of images). The segmented initial image is then used as an atlas image to automate the segmentation of other images in the MRI scans (3-D space). The processes include: ROI labeling, atlas construction and registration, and morphological transform correspondence pixels (in terms of feature and intensity value) between the atlas (template) image and the targeted image based on the prior atlas information and non-rigid image registration methods.

  20. Molecular Imaging with MRI: Potential Application in Pancreatic Cancer

    PubMed Central

    Chen, Chen; Wu, Chang Qiang; Chen, Tian Wu; Tang, Meng Yue; Zhang, Xiao Ming

    2015-01-01

    Despite the variety of approaches that have been improved to achieve a good understanding of pancreatic cancer (PC), the prognosis of PC remains poor, and the survival rates are dismal. The lack of early detection and effective interventions is the main reason. Therefore, considerable ongoing efforts aimed at identifying early PC are currently being pursued using a variety of methods. In recent years, the development of molecular imaging has made the specific targeting of PC in the early stage possible. Molecular imaging seeks to directly visualize, characterize, and measure biological processes at the molecular and cellular levels. Among different imaging technologies, the magnetic resonance (MR) molecular imaging has potential in this regard because it facilitates noninvasive, target-specific imaging of PC. This topic is reviewed in terms of the contrast agents for MR molecular imaging, the biomarkers related to PC, targeted molecular probes for MRI, and the application of MRI in the diagnosis of PC. PMID:26579537

  1. Impact of low signal intensity assessed by cine magnetic resonance imaging on detection of poorly viable myocardium in patients with prior myocardial infarction.

    PubMed

    Ota, Shingo; Tanimoto, Takashi; Orii, Makoto; Hirata, Kumiko; Shiono, Yasutsugu; Shimamura, Kunihiro; Matsuo, Yoshiki; Yamano, Takashi; Ino, Yasushi; Kitabata, Hironori; Yamaguchi, Tomoyuki; Kubo, Takashi; Tanaka, Atsushi; Imanishi, Toshio; Akasaka, Takashi

    2015-05-13

    Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) has been established as a modality to detect myocardial infarction (MI). However, the use of gadolinium contrast is limited in patients with advanced renal dysfunction. Although the signal intensity (SI) of infarct area assessed by cine MRI is low in some patients with prior MI, the prevalence and clinical significance of low SI has not been evaluated. The aim of this study was to evaluate how low SI assessed by cine MRI may relate to the myocardial viability in patients with prior MI. Fifty patients with prior MI underwent both cine MRI and LGE-MRI. The left ventricle was divided into 17 segments. The presence of low SI and the wall motion score (WMS) of each segment were assessed by cine MRI. The transmural extent of infarction was evaluated by LGE-MRI. LGE was detected in 329 of all 850 segments (39%). The low SI assessed by cine MRI was detected in 105 of 329 segments with LGE (32%). All segments with low SI had LGE. Of all 329 segments with LGE, the segments with low SI showed greater transmural extent of infarction (78 [72 - 84] % versus 53 [38 - 72] %, P < 0.01), thinner wall (4.0[3.1 - 4.8] mm versus 6.5 [5.2 - 8.1] mm, P < 0.01), and higher WMS (4.0 [4.0 - 4.0] versus 2.0 [2.0 - 3.0], P < 0.01). The low SI assessed by cine MRI may be effective for detecting poorly viable myocardium in patients with prior MI.

  2. MRI and PET image fusion using fuzzy logic and image local features.

    PubMed

    Javed, Umer; Riaz, Muhammad Mohsin; Ghafoor, Abdul; Ali, Syed Sohaib; Cheema, Tanveer Ahmed

    2014-01-01

    An image fusion technique for magnetic resonance imaging (MRI) and positron emission tomography (PET) using local features and fuzzy logic is presented. The aim of proposed technique is to maximally combine useful information present in MRI and PET images. Image local features are extracted and combined with fuzzy logic to compute weights for each pixel. Simulation results show that the proposed scheme produces significantly better results compared to state-of-art schemes.

  3. The physics of functional magnetic resonance imaging (fMRI)

    NASA Astrophysics Data System (ADS)

    Buxton, Richard B.

    2013-09-01

    Functional magnetic resonance imaging (fMRI) is a methodology for detecting dynamic patterns of activity in the working human brain. Although the initial discoveries that led to fMRI are only about 20 years old, this new field has revolutionized the study of brain function. The ability to detect changes in brain activity has a biophysical basis in the magnetic properties of deoxyhemoglobin, and a physiological basis in the way blood flow increases more than oxygen metabolism when local neural activity increases. These effects translate to a subtle increase in the local magnetic resonance signal, the blood oxygenation level dependent (BOLD) effect, when neural activity increases. With current techniques, this pattern of activation can be measured with resolution approaching 1 mm3 spatially and 1 s temporally. This review focuses on the physical basis of the BOLD effect, the imaging methods used to measure it, the possible origins of the physiological effects that produce a mismatch of blood flow and oxygen metabolism during neural activation, and the mathematical models that have been developed to understand the measured signals. An overarching theme is the growing field of quantitative fMRI, in which other MRI methods are combined with BOLD methods and analyzed within a theoretical modeling framework to derive quantitative estimates of oxygen metabolism and other physiological variables. That goal is the current challenge for fMRI: to move fMRI from a mapping tool to a quantitative probe of brain physiology.

  4. The physics of functional magnetic resonance imaging (fMRI)

    PubMed Central

    Buxton, Richard B

    2015-01-01

    Functional magnetic resonance imaging (fMRI) is a methodology for detecting dynamic patterns of activity in the working human brain. Although the initial discoveries that led to fMRI are only about 20 years old, this new field has revolutionized the study of brain function. The ability to detect changes in brain activity has a biophysical basis in the magnetic properties of deoxyhemoglobin, and a physiological basis in the way blood flow increases more than oxygen metabolism when local neural activity increases. These effects translate to a subtle increase in the local magnetic resonance signal, the blood oxygenation level dependent (BOLD) effect, when neural activity increases. With current techniques, this pattern of activation can be measured with resolution approaching 1 mm3 spatially and 1 s temporally. This review focuses on the physical basis of the BOLD effect, the imaging methods used to measure it, the possible origins of the physiological effects that produce a mismatch of blood flow and oxygen metabolism during neural activation, and the mathematical models that have been developed to understand the measured signals. An overarching theme is the growing field of quantitative fMRI, in which other MRI methods are combined with BOLD methods and analyzed within a theoretical modeling framework to derive quantitative estimates of oxygen metabolism and other physiological variables. That goal is the current challenge for fMRI: to move fMRI from a mapping tool to a quantitative probe of brain physiology. PMID:24006360

  5. Magnetic resonance imaging (MRI): A review of genetic damage investigations.

    PubMed

    Vijayalaxmi; Fatahi, Mahsa; Speck, Oliver

    2015-01-01

    Magnetic resonance imaging (MRI) is a powerful, non-invasive diagnostic medical imaging technique widely used to acquire detailed information about anatomy and function of different organs in the body, in both health and disease. It utilizes electromagnetic fields of three different frequency bands: static magnetic field (SMF), time-varying gradient magnetic fields (GMF) in the kHz range and pulsed radiofrequency fields (RF) in the MHz range. There have been some investigations examining the extent of genetic damage following exposure of bacterial and human cells to all three frequency bands of electromagnetic fields, as used during MRI: the rationale for these studies is the well documented evidence of positive correlation between significantly increased genetic damage and carcinogenesis. Overall, the published data were not sufficiently informative and useful because of the small sample size, inappropriate comparison of experimental groups, etc. Besides, when an increased damage was observed in MRI-exposed cells, the fate of such lesions was not further explored from multiple 'down-stream' events. This review provides: (i) information on the basic principles used in MRI technology, (ii) detailed experimental protocols, results and critical comments on the genetic damage investigations thus far conducted using MRI equipment and, (iii) a discussion on several gaps in knowledge in the current scientific literature on MRI. Comprehensive, international, multi-centered collaborative studies, using a common and widely used MRI exposure protocol (cardiac or brain scan) incorporating several genetic/epigenetic damage end-points as well as epidemiological investigations, in large number of individuals/patients are warranted to reduce and perhaps, eliminate uncertainties raised in genetic damage investigations in cells exposed in vitro and in vivo to MRI.

  6. Simultaneous imaging using Si-PM-based PET and MRI for development of an integrated PET/MRI system

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Watabe, Tadashi; Watabe, Hiroshi; Aoki, Masaaki; Sugiyama, Eiji; Imaizumi, Masao; Kanai, Yasukazu; Shimosegawa, Eku; Hatazawa, Jun

    2012-01-01

    The silicon photomultiplier (Si-PM) is a promising photo-detector for PET for use in magnetic resonance imaging (MRI) systems because it has high gain and is insensitive to static magnetic fields. Recently we developed a Si-PM-based depth-of-interaction PET system for small animals and performed simultaneous measurements by combining the Si-PM-based PET and the 0.15 T permanent MRI to test the interferences between the Si-PM-based PET and an MRI. When the Si-PM was inside the MRI and installed around the radio frequency (RF) coil of the MRI, significant noise from the RF sequence of the MRI was observed in the analog signals of the PET detectors. However, we did not observe any artifacts in the PET images; fluctuation increased in the count rate of the Si-PM-based PET system. On the MRI side, there was significant degradation of the signal-to-noise ratio (S/N) in the MRI images compared with those without PET. By applying noise reduction procedures, the degradation of the S/N was reduced. With this condition, simultaneous measurements of a rat brain using a Si-PM-based PET and an MRI were made with some degradation in the MRI images. We conclude that simultaneous measurements are possible using Si-PM-based PET and MRI.

  7. Breast imaging with ultrasound tomography: a comparative study with MRI

    NASA Astrophysics Data System (ADS)

    Ranger, Bryan; Littrup, Peter; Duric, Neb; Li, Cuiping; Schmidt, Steven; Lupinacci, Jessica; Myc, Lukasz; Szczepanski, Amy; Rama, Olsi; Bey-Knight, Lisa

    2010-03-01

    The purpose of this study was to investigate the performance of an ultrasound tomography (UST) prototype relative to magnetic resonance (MR) for imaging overall breast anatomy and accentuating tumors relative to background tissue. The study was HIPAA compliant, approved by the Institutional Review Board, and performed after obtaining the requisite informed consent. Twenty-three patients were imaged with MR and the UST prototype. T1 weighted images with fat saturation, with and without gadolinium enhancement, were used to examine anatomical structures and tumors, while T2 weighted images were used to identify cysts. The UST scans generated sound speed, attenuation, and reflection images. A qualitative visual comparison of the MRI and UST images was then used to identify anatomical similarities. A more focused approach that involved a comparison of reported masses, lesion volumes, and breast density was used to quantify the findings from the visual assessment. Our acoustic tomography prototype imaged distributions of fibrous stroma, parenchyma, fatty tissues, and lesions in patterns similar to those seen in the MR images. The range of thresholds required to establish tumor volume equivalency between MRI and UST suggested that a universal threshold for isolating masses relative to background tissue is feasible with UST. UST has demonstrated the ability to visualize and characterize breast tissues in a manner comparable to MRI. Thresholding techniques accentuate masses relative to background anatomy, which may prove clinically useful for early cancer detection.

  8. Few-view cone-beam CT reconstruction with deformed prior image

    SciTech Connect

    Zhang, Hua; Ouyang, Luo; Wang, Jing E-mail: jing.wang@utsouthwestern.edu; Huang, Jing; Ma, Jianhua E-mail: jing.wang@utsouthwestern.edu; Chen, Wufan

    2014-12-15

    Purpose: Prior images can be incorporated into the image reconstruction process to improve the quality of subsequent cone-beam CT (CBCT) images from sparse-view or low-dose projections. The purpose of this work is to develop a deformed prior image-based reconstruction (DPIR) strategy to mitigate the deformation between the prior image and the target image. Methods: The deformed prior image is obtained by a projection-based registration approach. Specifically, the deformation vector fields used to deform the prior image are estimated through iteratively matching the forward projection of the deformed prior image and the measured on-treatment projections. The deformed prior image is then used as the prior image in the standard prior image constrained compressed sensing (PICCS) algorithm. A simulation study on an XCAT phantom and a clinical study on a head-and-neck cancer patient were conducted to evaluate the performance of the proposed DPIR strategy. Results: The deformed prior image matches the geometry of the on-treatment CBCT more closely as compared to the original prior image. Consequently, the performance of the DPIR strategy from few-view projections is improved in comparison to the standard PICCS algorithm, based on both visual inspection and quantitative measures. In the XCAT phantom study using 20 projections, the average root mean squared error is reduced from 14% in PICCS to 10% in DPIR, and the average universal quality index increases from 0.88 in PICCS to 0.92 in DPIR. Conclusions: The present DPIR approach provides a practical solution to the mismatch problem between the prior image and target image, which improves the performance of the original PICCS algorithm for CBCT reconstruction from few-view or low-dose projections.

  9. Comparisons of EPR imaging and T1-weighted MRI for efficient imaging of nitroxyl contrast agents.

    PubMed

    Matsumoto, Ken-ichiro; Narazaki, Michiko; Ikehira, Hiroo; Anzai, Kazunori; Ikota, Nobuo

    2007-07-01

    The resolution and signal to noise ratio of EPR imaging and T(1)-weighted MRI were compared using an identical phantom. Several solutions of nitroxyl contrast agents with different EPR spectral shapes were tested. The feasibility of T(1)-weighted MRI to detect nitroxyl contrast agents was described. T(1)-weighted MRI can detect nitroxyl contrast agents with a complicated EPR spectrum easier and quicker; however, T(1)-weighted MRI has less quantitative ability especially for lipophilic nitroxyl contrast agents, because T(1)-relaxivity, i.e. accessibility to water, is affected by the hydrophilic/hydrophobic micro-environment of a nitroxyl contrast agent. The less quantitative ability of T(1)-weighted MRI may not be a disadvantage of redox imaging, which obtains reduction rate of a nitroxyl contrast. Therefore, T(1)-weighted MRI has a great advantage to check the pharmacokinetics of newly modified and/or designed nitroxyl contrast agents. PMID:17433743

  10. Opening the black box: imaging nanoparticle transport with MRI

    NASA Astrophysics Data System (ADS)

    Phoenix, V.; Holmes, W. M.

    2009-12-01

    While most renown for its use in medicine, magnetic resonance imaging (MRI) has tremendous potential in the study of environmental processes. Its ability to non-invasively image inside materials that are opaque to other imaging methods (in particular light based techniques) is a particular strength. MRI has already been used, for example, to study fluid flow in rocks and image mass transport and biogeochemical processes in biofilms [1-4]. Here, we report of the use of MRI to image nanoparticle transport through porous geologic media (in this case packed gravel columns). Packed column experiments are key to understanding nanoparticulate transport in porous geologic media. Whilst highly informative, the data obtained can be a bulk average of a complex and heterogeneous array of interactions within the column. Natural environmental systems are often complex, displaying heterogeneity in geometry, hydrodynamics, geochemistry and microbiology throughout. MRI enables us to quantify better how this heterogeneity may influence nanoparticle transport and fate by enabling us to look inside the column and image the movement of nanoparticles within. To make the nanoparticle readily visible to MRI, it is labelled with a paramagnetic tag (commonly gadolinium). Indeed, a wide variety of off-the-shelf paramagnetically tagged nanoparticles and macromolecules are available, each with different properties enabling us to explore the impact of particle charge, size etc on their transport behaviour. In this preliminary study, packed columns of quartz or marble based gravels (approx 5 mm diameter) were first imaged to check their suitability for MR imaging. This was done as geologic material can contain sufficiently high concentrations of ferro- and paramagnetic ions to induce unwanted artefacts in the MR image. All gravels imaged (Rose quartz, Creswick quartz gravel and Ben Deulin white marble) produced minimal or no artefacts. A solution of the nanoparticle GadoCELLTrack (BioPAL), was

  11. SQUID-sensor-based ultra-low-field MRI calibration with phantom images: Towards quantitative imaging

    NASA Astrophysics Data System (ADS)

    Dabek, Juhani; Vesanen, Panu T.; Zevenhoven, Koos C. J.; Nieminen, Jaakko O.; Sepponen, Raimo; Ilmoniemi, Risto J.

    2012-11-01

    In ultra-low-field magnetic resonance imaging (ULF MRI), measured resonance signals oscillate at Larmor frequencies around 1 kHz compared to even above 100 MHz in high-field MRI. Thus, detection by induction coils in ULF MRI is not feasible, whereas superconducting quantum interference device (SQUID) sensors can measure these femtotesla-level signals. The signal-to-noise ratio is enhanced by prepolarization in a field that is typically 100-1000 times higher than the field during acquisition. Based on both measurements and simulations, a procedure for calibrating a SQUID-sensor-based MRI system with MR images is presented in this article. Magnetoencephalography (MEG) can be integrated with ULF MRI, and may also benefit from such a calibration procedure. Conventionally, electromagnet probe signals have been used for the SQUID-sensor calibration in MEG; the presented ULF-MRI-based approach using an imaging phantom could replace this procedure in hybrid MEG-MRI or ULF MRI alone. The necessary theory is provided here with experimental verification. The calibration procedure opens the possibility of performing quantitative ULF MRI without sample-specific reference scans.

  12. SQUID-sensor-based ultra-low-field MRI calibration with phantom images: towards quantitative imaging.

    PubMed

    Dabek, Juhani; Vesanen, Panu T; Zevenhoven, Koos C J; Nieminen, Jaakko O; Sepponen, Raimo; Ilmoniemi, Risto J

    2012-11-01

    In ultra-low-field magnetic resonance imaging (ULF MRI), measured resonance signals oscillate at Larmor frequencies around 1 kHz compared to even above 100 MHz in high-field MRI. Thus, detection by induction coils in ULF MRI is not feasible, whereas superconducting quantum interference device (SQUID) sensors can measure these femtotesla-level signals. The signal-to-noise ratio is enhanced by prepolarization in a field that is typically 100-1000 times higher than the field during acquisition. Based on both measurements and simulations, a procedure for calibrating a SQUID-sensor-based MRI system with MR images is presented in this article. Magnetoencephalography (MEG) can be integrated with ULF MRI, and may also benefit from such a calibration procedure. Conventionally, electromagnet probe signals have been used for the SQUID-sensor calibration in MEG; the presented ULF-MRI-based approach using an imaging phantom could replace this procedure in hybrid MEG-MRI or ULF MRI alone. The necessary theory is provided here with experimental verification. The calibration procedure opens the possibility of performing quantitative ULF MRI without sample-specific reference scans.

  13. Magnetic Particle Imaging (MPI) for NMR and MRI researchers

    NASA Astrophysics Data System (ADS)

    Saritas, Emine U.; Goodwill, Patrick W.; Croft, Laura R.; Konkle, Justin J.; Lu, Kuan; Zheng, Bo; Conolly, Steven M.

    2013-04-01

    Magnetic Particle Imaging (MPI) is a new tracer imaging modality that is gaining significant interest from NMR and MRI researchers. While the physics of MPI differ substantially from MRI, it employs hardware and imaging concepts that are familiar to MRI researchers, such as magnetic excitation and detection, pulse sequences, and relaxation effects. Furthermore, MPI employs the same superparamagnetic iron oxide (SPIO) contrast agents that are sometimes used for MR angiography and are often used for MRI cell tracking studies. These SPIOs are much safer for humans than iodine or gadolinium, especially for Chronic Kidney Disease (CKD) patients. The weak kidneys of CKD patients cannot safely excrete iodine or gadolinium, leading to increased morbidity and mortality after iodinated X-ray or CT angiograms, or after gadolinium-MRA studies. Iron oxides, on the other hand, are processed in the liver, and have been shown to be safe even for CKD patients. Unlike the “black blood” contrast generated by SPIOs in MRI due to increased T2∗ dephasing, SPIOs in MPI generate positive, “bright blood” contrast. With this ideal contrast, even prototype MPI scanners can already achieve fast, high-sensitivity, and high-contrast angiograms with millimeter-scale resolutions in phantoms and in animals. Moreover, MPI shows great potential for an exciting array of applications, including stem cell tracking in vivo, first-pass contrast studies to diagnose or stage cancer, and inflammation imaging in vivo. So far, only a handful of prototype small-animal MPI scanners have been constructed worldwide. Hence, MPI is open to great advances, especially in hardware, pulse sequence, and nanoparticle improvements, with the potential to revolutionize the biomedical imaging field.

  14. Multi-region labeling and segmentation using a graph topology prior and atlas information in brain images.

    PubMed

    Al-Shaikhli, Saif Dawood Salman; Yang, Michael Ying; Rosenhahn, Bodo

    2014-12-01

    Medical image segmentation and anatomical structure labeling according to the types of the tissues are important for accurate diagnosis and therapy. In this paper, we propose a novel approach for multi-region labeling and segmentation, which is based on a topological graph prior and the topological information of an atlas, using a modified multi-level set energy minimization method in brain images. We consider a topological graph prior and atlas information to evolve the contour based on a topological relationship presented via a graph relation. This novel method is capable of segmenting adjacent objects with very close gray level in low resolution brain image that would be difficult to segment correctly using standard methods. The topological information of an atlas are transformed to the topological graph of a low resolution (noisy) brain image to obtain region labeling. We explain our algorithm and show the topological graph prior and label transformation techniques to explain how it gives precise multi-region segmentation and labeling. The proposed algorithm is capable of segmenting and labeling different regions in noisy or low resolution MRI brain images of different modalities. We compare our approaches with other state-of-the-art approaches for multi-region labeling and segmentation.

  15. Prior data assisted compressed sensing: A novel MR imaging strategy for real time tracking of lung tumors

    SciTech Connect

    Yip, Eugene; Yun, Jihyun; Heikal, Amr A.; Wachowicz, Keith; Rathee, Satyapal; Gabos, Zsolt; Fallone, B. G.

    2014-08-15

    Purpose: Hybrid radiotherapy-MRI devices promise real time tracking of moving tumors to focus the radiation portals to the tumor during irradiation. This approach will benefit from the increased temporal resolution of MRI's data acquisition and reconstruction. In this work, the authors propose a novel spatial-temporal compressed sensing (CS) imaging strategy for the real time MRI–-prior data assisted compressed sensing (PDACS), which aims to improve the image quality of the conventional CS without significantly increasing reconstruction times. Methods: Conventional 2D CS requires a random sampling of partial k-space data, as well as an iterative reconstruction that simultaneously enforces the image's sparsity in a transform domain as well as maintains the fidelity to the acquired k-space. PDACS method requires the additional acquisition of the prior data, and for reconstruction, it additionally enforces fidelity to the prior k-space domain similar to viewsharing. In this work, the authors evaluated the proposed PDACS method by comparing its results to those obtained from the 2D CS and viewsharing methods when performed individually. All three methods are used to reconstruct images from lung cancer patients whose tumors move and who are likely to benefit from lung tumor tracking. The patients are scanned, using a 3T MRI, under free breathing using the fully sampled k-space with 2D dynamic bSSFP sequence in a sagittal plane containing lung tumor. These images form a reference set for the evaluation of the partial k-space methods. To create partial k-space, the fully sampled k-space is retrospectively undersampled to obtain a range of acquisition acceleration factors, and reconstructed with 2D-CS, PDACS, and viewshare methods. For evaluation, metrics assessing global image artifacts as well as tumor contour shape fidelity are determined from the reconstructed images. These analyses are performed both for the original 3T images and those at a simulated 0.5T

  16. MRI with hyperpolarised [1-13C]pyruvate detects advanced pancreatic preneoplasia prior to invasive disease in a mouse model

    PubMed Central

    Serrao, Eva M; Kettunen, Mikko I; Rodrigues, Tiago B; Dzien, Piotr; Wright, Alan J; Gopinathan, Aarthi; Gallagher, Ferdia A; Lewis, David Y; Frese, Kristopher K; Almeida, Jaime; Howat, William J; Tuveson, David A; Brindle, Kevin M

    2016-01-01

    Objectives Pancreatic cancer (PCa) is treatable by surgery when detected at an early stage. Non-invasive imaging methods able to detect both established tumours and their precursor lesions are needed to select patients for surgery. We investigated here whether pancreatic preneoplasia could be detected prior to the development of invasive cancers in genetically engineered mouse models of PCa using metabolic imaging. Design The concentrations of alanine and lactate and the activities of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) were measured in extracts prepared from the pancreas of animals at different stages of disease progression; from pancreatitis, through tissue with predominantly low-grade and then high-grade pancreatic intraepithelial neoplasia and then tumour. 13C magnetic resonance spectroscopic imaging (13C-MRSI) was used to measure non-invasively changes in 13C labelling of alanine and lactate with disease progression, following injection of hyperpolarised [1-13C]pyruvate. Results Progressive decreases in the alanine/lactate concentration ratio and ALT/LDH activity ratio with disease progression were accompanied by a corresponding decrease in the [1-13C]alanine/[1-13C]lactate signal ratio observed in 13C-MRSI images of the pancreas. Conclusions Metabolic imaging with hyperpolarised [1-13C]pyruvate enables detection and monitoring of the progression of PCa precursor lesions. Translation of this MRI technique to the clinic has the potential to improve the management of patients at high risk of developing PCa. PMID:26347531

  17. Imaging industry expectations for compressed sensing in MRI

    NASA Astrophysics Data System (ADS)

    King, Kevin F.; Kanwischer, Adriana; Peters, Rob

    2015-09-01

    Compressed sensing requires compressible data, incoherent acquisition and a nonlinear reconstruction algorithm to force creation of a compressible image consistent with the acquired data. MRI images are compressible using various transforms (commonly total variation or wavelets). Incoherent acquisition of MRI data by appropriate selection of pseudo-random or non-Cartesian locations in k-space is straightforward. Increasingly, commercial scanners are sold with enough computing power to enable iterative reconstruction in reasonable times. Therefore integration of compressed sensing into commercial MRI products and clinical practice is beginning. MRI frequently requires the tradeoff of spatial resolution, temporal resolution and volume of spatial coverage to obtain reasonable scan times. Compressed sensing improves scan efficiency and reduces the need for this tradeoff. Benefits to the user will include shorter scans, greater patient comfort, better image quality, more contrast types per patient slot, the enabling of previously impractical applications, and higher throughput. Challenges to vendors include deciding which applications to prioritize, guaranteeing diagnostic image quality, maintaining acceptable usability and workflow, and acquisition and reconstruction algorithm details. Application choice depends on which customer needs the vendor wants to address. The changing healthcare environment is putting cost and productivity pressure on healthcare providers. The improved scan efficiency of compressed sensing can help alleviate some of this pressure. Image quality is strongly influenced by image compressibility and acceleration factor, which must be appropriately limited. Usability and workflow concerns include reconstruction time and user interface friendliness and response. Reconstruction times are limited to about one minute for acceptable workflow. The user interface should be designed to optimize workflow and minimize additional customer training. Algorithm

  18. Image segmentation and 3D visualization for MRI mammography

    NASA Astrophysics Data System (ADS)

    Li, Lihua; Chu, Yong; Salem, Angela F.; Clark, Robert A.

    2002-05-01

    MRI mammography has a number of advantages, including the tomographic, and therefore three-dimensional (3-D) nature, of the images. It allows the application of MRI mammography to breasts with dense tissue, post operative scarring, and silicon implants. However, due to the vast quantity of images and subtlety of difference in MR sequence, there is a need for reliable computer diagnosis to reduce the radiologist's workload. The purpose of this work was to develop automatic breast/tissue segmentation and visualization algorithms to aid physicians in detecting and observing abnormalities in breast. Two segmentation algorithms were developed: one for breast segmentation, the other for glandular tissue segmentation. In breast segmentation, the MRI image is first segmented using an adaptive growing clustering method. Two tracing algorithms were then developed to refine the breast air and chest wall boundaries of breast. The glandular tissue segmentation was performed using an adaptive thresholding method, in which the threshold value was spatially adaptive using a sliding window. The 3D visualization of the segmented 2D slices of MRI mammography was implemented under IDL environment. The breast and glandular tissue rendering, slicing and animation were displayed.

  19. [Brain development of infant and MRI by diffusion tensor imaging].

    PubMed

    Dubois, J; Dehaene-Lambertz, G; Mangin, J-F; Le Bihan, D; Hüppi, P S; Hertz-Pannier, L

    2012-01-01

    Studying how the brain develops and becomes functional is important to understand how the man has been able to develop specific cognitive abilities, and to comprehend the complexity of some developmental pathologies. Thanks to magnetic resonance imaging (MRI), it is now possible to image the baby's immature brain and to consider subtle correlations between the brain anatomical development and the early acquisition of cognitive functions. Dedicated methodologies for image acquisition and post-treatment must then be used because the size of cerebral structures and the image contrast are very different in comparison with the adult brain, and because the examination length is a major constraint. Two recent studies have evaluated the developing brain under an original perspective. The first one has focused on cortical folding in preterm newborns, from 6 to 8 months of gestational age, assessed with T2-weighted conventional MRI. The second study has mapped the organization and maturation of white matter fiber bundles in 1- to 4-month-old healthy infants with diffusion tensor imaging (DTI). Both studies have enabled to highlight spatio-temporal differences in the brain regions' maturation, as well as early anatomical asymmetries between cerebral hemispheres. These studies emphasize the potential of MRI to evaluate brain development compared with the infant's psychomotor acquisitions after birth.

  20. Lossless Compression on MRI Images Using SWT.

    PubMed

    Anusuya, V; Raghavan, V Srinivasa; Kavitha, G

    2014-10-01

    Medical image compression is one of the growing research fields in biomedical applications. Most medical images need to be compressed using lossless compression as each pixel information is valuable. With the wide pervasiveness of medical imaging applications in health-care settings and the increased interest in telemedicine technologies, it has become essential to reduce both storage and transmission bandwidth requirements needed for archival and communication of related data, preferably by employing lossless compression methods. Furthermore, providing random access as well as resolution and quality scalability to the compressed data has become of great utility. Random access refers to the ability to decode any section of the compressed image without having to decode the entire data set. The system proposes to implement a lossless codec using an entropy coder. 3D medical images are decomposed into 2D slices and subjected to 2D-stationary wavelet transform (SWT). The decimated coefficients are compressed in parallel using embedded block coding with optimized truncation of the embedded bit stream. These bit streams are decoded and reconstructed using inverse SWT. Finally, the compression ratio (CR) is evaluated to prove the efficiency of the proposal. As an enhancement, the proposed system concentrates on minimizing the computation time by introducing parallel computing on the arithmetic coding stage as it deals with multiple subslices.

  1. Functional Cardiac Magnetic Resonance Imaging (MRI) in the Assessment of Myocardial Viability and Perfusion

    PubMed Central

    2003-01-01

    Executive Summary Objective The objective of this health technology policy assessment was to determine the effectiveness safety and cost-effectiveness of using functional cardiac magnetic resonance imaging (MRI) for the assessment of myocardial viability and perfusion in patients with coronary artery disease and left ventricular dysfunction. Results Functional MRI has become increasingly investigated as a noninvasive method for assessing myocardial viability and perfusion. Most patients in the published literature have mild to moderate impaired LV function. It is possible that the severity of LV dysfunction may be an important factor that can alter the diagnostic accuracy of imaging techniques. There is some evidence of comparable or better performance of functional cardiac MRI for the assessment of myocardial viability and perfusion compared with other imaging techniques. However limitations to most of the studies included: Functional cardiac MRI studies that assess myocardial viability and perfusion have had small sample sizes. Some studies assessed myocardial viability/perfusion in patients who had already undergone revascularization, or excluded patients with a prior MI (Schwitter et al., 2001). Lack of explicit detail of patient recruitment. Patients with LVEF >35%. Interstudy variability in post MI imaging time(including acute or chronic MI), when patients with a prior MI were included. Poor interobserver agreement (kappa statistic) in the interpretation of the results. Traditionally, 0.80 is considered “good”. Cardiac MRI measurement of myocardial perfusion to as an adjunct tool to help diagnose CAD (prior to a definitive coronary angiography) has also been examined in some studies, with methodological limitations, yielding comparable results. Many studies examining myocardial viability and perfusion report on the accuracy of imaging methods with limited data on long-term patient outcome and management. Kim et al. (2000) revealed that the transmural

  2. Suppressing Multi-Channel Ultra-Low-Field MRI Measurement Noise Using Data Consistency and Image Sparsity

    PubMed Central

    Lin, Fa-Hsuan; Vesanen, Panu T.; Hsu, Yi-Cheng; Nieminen, Jaakko O.; Zevenhoven, Koos C. J.; Dabek, Juhani; Parkkonen, Lauri T.; Simola, Juha; Ahonen, Antti I.; Ilmoniemi, Risto J.

    2013-01-01

    Ultra-low-field (ULF) MRI (B0 = 10–100 µT) typically suffers from a low signal-to-noise ratio (SNR). While SNR can be improved by pre-polarization and signal detection using highly sensitive superconducting quantum interference device (SQUID) sensors, we propose to use the inter-dependency of the k-space data from highly parallel detection with up to tens of sensors readily available in the ULF MRI in order to suppress the noise. Furthermore, the prior information that an image can be sparsely represented can be integrated with this data consistency constraint to further improve the SNR. Simulations and experimental data using 47 SQUID sensors demonstrate the effectiveness of this data consistency constraint and sparsity prior in ULF-MRI reconstruction. PMID:23626710

  3. Current imaging techniques in rheumatology: MRI, scintigraphy and PET

    PubMed Central

    Sudoł-Szopińska, Iwona; Ćwikła, Jarosław B.

    2013-01-01

    Summary The first-line imaging technique for diagnosis inflammation in musculo-skeletal organs in rheumatoid arthritis (RA) is planar X-ray examination, which was for many years the first and the only single tool for RA diagnostics and response evaluation. Today, in the era of more aggressive RA treatment, ultrasound examination (US) and magnetic resonance imaging (MRI) are also frequently used. US is used to detect early signs of inflammation within the soft tissue. MRI allows to assess the soft tissue and bone marrow involvement in case of inflammation and/or infection. MRI is capable of detecting more inflammatory lesions and erosions than US, X-ray, or CT. Standard scintigraphy plays a crucial role, and data from positron emission tomography (PET) are also promising. These functional imaging techniques are used in detection of inflammation and/or infection in case of ambiguous results being obtained by other techniques or at other clinics. In patients with RA, scintigraphy plays a key role in the differential diagnosis of hip, knee, etc. endoprosthesis disorders, including mechanical or septic loosening. PMID:24115960

  4. Vocal tract imaging: a comparison of MRI and EBCT

    NASA Astrophysics Data System (ADS)

    Story, Brad H.; Hoffman, Eric A.; Titze, Ingo R.

    1996-04-01

    Vocal tract imaging for the vowels /i/ and /a/ using both EBCT and MRI was carried out for one subject (29 yr old male, native of midwestern United States) using an Imatron C-150 electron beam CT scanner and a GE Signa 1.5 Tesla scanner, respectively. Each image set was analyzed using a general display and quantitation package called VIDATM (Volumetric Image Display and Analysis). The image analysis consisted of segmenting the airspace from the surrounding tissue, obtaining a 3D vocal tract shape via shape based interpolation, and finally using an iterative bisection algorithm to determine the vocal tract area function. The results show that the 3D representations of the vocal tract shapes derived from EBCT show subtle deformations of the airway by articulatory structures and teeth that are not observed in the MRI based representations. Shaded surface renderings of each vocal tract shape and for each imaging technique are shown and the apparent trade-offs between the two imaging methods are discussed.

  5. Brain CT and MRI: differential diagnosis of imaging findings.

    PubMed

    Masdeu, Joseph C; Gadhia, Rajan; Faridar, Alireza

    2016-01-01

    Following a traditional approach, in Chapters 5 and 14-29 in the previous volume, diverse brain diseases are listed and their imaging findings described in detail. In this chapter the approach is from the imaging finding to the disease: for instance, what list of diseases can give rise to a contrast-enhancing mass in the cerebellopontine angle? Imaging findings that are reviewed in succession include the location of the lesion, its multiplicity and symmetry, its volume, ranging from atrophy to mass effect, its homogeneity, its density, measurable by computed tomography (CT), its appearance on T1, T2, and diffusion magnetic resonance imaging (MRI), and, finally, its characteristics after the infusion of intravenous contrast. A differential diagnosis for each finding is provided. While the approach adopted in this chapter is unconventional, we hope that it will be most helpful to anyone reading images. Furthermore, it could serve as the basis to create or complete image databases to guide in the interpretation of brain CT and MRI. PMID:27430457

  6. SU-E-J-257: Image Artifacts Caused by Implanted Calypso Beacons in MRI Studies

    SciTech Connect

    Amro, H; Chetty, I; Gordon, J; Wen, N

    2014-06-01

    Purpose: The presence of Calypso Beacon-transponders in patients can cause artifacts during MRI imaging studies. This could be a problem for post-treatment follow up of cancer patients using MRI studies to evaluate metastasis and for functional imaging studies.This work assesses (1) the volume immediately surrounding the transponders that will not be visualized by the MRI due to the beacons, and (2) the dependence of the non-visualized volume on beacon orientation, and scanning techniques. Methods: Two phantoms were used in this study (1) water filled box, (2) and a 2300 cc block of pork meat. Calypso beacons were implanted in the phantoms both in parallel and perpendicular orientations with respect to the MR scanner magnetic field. MR image series of the phantom were obtained with on a 1.0T high field open MR-SIM with multiple pulse sequences, for example, T1-weighted fast field echo and T2-weighted turbo spin echo. Results: On average, a no-signal region with 2 cm radius and 3 cm length was measured. Image artifacts are more significant when beacons are placed parallel to scanner magnetic field; the no-signal area around the beacon was about 0.5 cm larger in orthogonal orientation. The no-signal region surrounding the beacons slightly varies in dimension for the different pulse sequences. Conclusion: The use of Calypso beacons can prohibit the use of MRI studies in post-treatment assessments, especially in the immediate region surrounding the implanted beacon. A characterization of the MR scanner by identifying the no-signal regions due to implanted beacons is essential. This may render the use of Calypso beacons useful for some cases and give the treating physician a chance to identify those patients prior to beacon implantation.

  7. Clinical validation of SPECT and CT/MRI image registration in radiolabeled monoclonal antibody studies of colorectal carcinoma

    SciTech Connect

    Scott, A.M.; Macapinlac, H.A.; Divgi, C.R.

    1994-12-01

    Registration methods combine the anatomic localizing ability of CT or MRI with SPECT images of radiolabeled monocional antibodies (Mabs), allowing the accurate staging of patients prior to surgery or following treatment. Twenty-four patients (15 males and 9 females, mean age 55 yr, range 29-70 yr) were studied with this technique. Ten patients had suspected colorectal cancer recurrence and were infused with 10 mCi of {sup 131}I-CC49 prior to staging laparotomy. Fourteen patients treated in a Phase 1 radioimmunotherapy study with {sup 131}I-CC49 were also studied. All patients underwent SPECT imaging of the abdomen and pelvis 5-7 days following infusion of Mab. Phantom studies demonstrated a 3.6-mm surface fitting mean accurracy of datasets for the liver and 1.8 mm for an intrahepatic tumor. In the presurgical group, SPECT and CT/MRI registration allowed more accurate identification of uptake abnormal sites. Areas of metastatic disease > 1 cm confirmed at surgery were found in six of nine patients with liver lesions and in two patients with extrahepatic (including one patient with pelvic) disease. In patients imaged following radioimmunotherapy, all lesions > 1.5 cm seen on CT/MRI were identified, and activity distribution in tumor and normal tissue could be more accurately assessed. Routine registration of SPECT and CT/MRI images is feasible and allows more accurate anatomic assessment of sites of abnormal uptake in radiolabeled Mab studies. 41 refs., 5 figs., 2 tabs.

  8. Automated identification of brain tumors from single MR images based on segmentation with refined patient-specific priors.

    PubMed

    Sanjuán, Ana; Price, Cathy J; Mancini, Laura; Josse, Goulven; Grogan, Alice; Yamamoto, Adam K; Geva, Sharon; Leff, Alex P; Yousry, Tarek A; Seghier, Mohamed L

    2013-01-01

    Brain tumors can have different shapes or locations, making their identification very challenging. In functional MRI, it is not unusual that patients have only one anatomical image due to time and financial constraints. Here, we provide a modified automatic lesion identification (ALI) procedure which enables brain tumor identification from single MR images. Our method rests on (A) a modified segmentation-normalization procedure with an explicit "extra prior" for the tumor and (B) an outlier detection procedure for abnormal voxel (i.e., tumor) classification. To minimize tissue misclassification, the segmentation-normalization procedure requires prior information of the tumor location and extent. We therefore propose that ALI is run iteratively so that the output of Step B is used as a patient-specific prior in Step A. We test this procedure on real T1-weighted images from 18 patients, and the results were validated in comparison to two independent observers' manual tracings. The automated procedure identified the tumors successfully with an excellent agreement with the manual segmentation (area under the ROC curve = 0.97 ± 0.03). The proposed procedure increases the flexibility and robustness of the ALI tool and will be particularly useful for lesion-behavior mapping studies, or when lesion identification and/or spatial normalization are problematic.

  9. Complete fourier direct magnetic resonance imaging (CFD-MRI) for diffusion MRI

    PubMed Central

    Özcan, Alpay

    2013-01-01

    The foundation for an accurate and unifying Fourier-based theory of diffusion weighted magnetic resonance imaging (DW–MRI) is constructed by carefully re-examining the first principles of DW–MRI signal formation and deriving its mathematical model from scratch. The derivations are specifically obtained for DW–MRI signal by including all of its elements (e.g., imaging gradients) using complex values. Particle methods are utilized in contrast to conventional partial differential equations approach. The signal is shown to be the Fourier transform of the joint distribution of number of the magnetic moments (at a given location at the initial time) and magnetic moment displacement integrals. In effect, the k-space is augmented by three more dimensions, corresponding to the frequency variables dual to displacement integral vectors. The joint distribution function is recovered by applying the Fourier transform to the complete high-dimensional data set. In the process, to obtain a physically meaningful real valued distribution function, phase corrections are applied for the re-establishment of Hermitian symmetry in the signal. Consequently, the method is fully unconstrained and directly presents the distribution of displacement integrals without any assumptions such as symmetry or Markovian property. The joint distribution function is visualized with isosurfaces, which describe the displacement integrals, overlaid on the distribution map of the number of magnetic moments with low mobility. The model provides an accurate description of the molecular motion measurements via DW–MRI. The improvement of the characterization of tissue microstructure leads to a better localization, detection and assessment of biological properties such as white matter integrity. The results are demonstrated on the experimental data obtained from an ex vivo baboon brain. PMID:23596401

  10. Designing Image Operators for MRI-PET Image Fusion of the Brain

    SciTech Connect

    Marquez, Jorge; Gastelum, Alfonso; Padilla, Miguel A.

    2006-09-08

    Our goal is to obtain images combining in a useful and precise way the information from 3D volumes of medical imaging sets. We address two modalities combining anatomy (Magnetic Resonance Imaging or MRI) and functional information (Positron Emission Tomography or PET). Commercial imaging software offers image fusion tools based on fixed blending or color-channel combination of two modalities, and color Look-Up Tables (LUTs), without considering the anatomical and functional character of the image features. We used a sensible approach for image fusion taking advantage mainly from the HSL (Hue, Saturation and Luminosity) color space, in order to enhance the fusion results. We further tested operators for gradient and contour extraction to enhance anatomical details, plus other spatial-domain filters for functional features corresponding to wide point-spread-function responses in PET images. A set of image-fusion operators was formulated and tested on PET and MRI acquisitions.

  11. Designing Image Operators for MRI-PET Image Fusion of the Brain

    NASA Astrophysics Data System (ADS)

    Márquez, Jorge; Gastélum, Alfonso; Padilla, Miguel A.

    2006-09-01

    Our goal is to obtain images combining in a useful and precise way the information from 3D volumes of medical imaging sets. We address two modalities combining anatomy (Magnetic Resonance Imaging or MRI) and functional information (Positron Emission Tomography or PET). Commercial imaging software offers image fusion tools based on fixed blending or color-channel combination of two modalities, and color Look-Up Tables (LUTs), without considering the anatomical and functional character of the image features. We used a sensible approach for image fusion taking advantage mainly from the HSL (Hue, Saturation and Luminosity) color space, in order to enhance the fusion results. We further tested operators for gradient and contour extraction to enhance anatomical details, plus other spatial-domain filters for functional features corresponding to wide point-spread-function responses in PET images. A set of image-fusion operators was formulated and tested on PET and MRI acquisitions.

  12. Functional MRI studies of human vision on a clinical imager

    SciTech Connect

    George, J.S.; Lewine, J.D.; Aine, C.J.; van Hulsteyn, D.; Wood, C.C. ); Sanders, J.; Maclin, E. ); Belliveau, J.W. ); Caprihan, A. )

    1992-01-01

    During the past decade, Magnetic Resonance Imaging (MRI) has become the method of choice for imaging the anatomy of the human brain. Recently, Belliveau and colleagues have reported the use of echo planar magnetic resonance imaging (EPI) to image patterns of neural activity. Here, we report functional MR imaging in response to visual stimulation without the use of contrast agents, and without the extensive hardware modifications required for EPI. Regions of activity were observed near the expected locations of V1, V2 and possibly V3 and another active region was observed near the parietal-occipital sulcus on the superior surface of the cerebrum. These locations are consistent with sources observed in neuromagnetic studies of the human visual response.

  13. Functional MRI studies of human vision on a clinical imager

    SciTech Connect

    George, J.S.; Lewine, J.D.; Aine, C.J.; van Hulsteyn, D.; Wood, C.C.; Sanders, J.; Maclin, E.; Belliveau, J.W.; Caprihan, A.

    1992-09-01

    During the past decade, Magnetic Resonance Imaging (MRI) has become the method of choice for imaging the anatomy of the human brain. Recently, Belliveau and colleagues have reported the use of echo planar magnetic resonance imaging (EPI) to image patterns of neural activity. Here, we report functional MR imaging in response to visual stimulation without the use of contrast agents, and without the extensive hardware modifications required for EPI. Regions of activity were observed near the expected locations of V1, V2 and possibly V3 and another active region was observed near the parietal-occipital sulcus on the superior surface of the cerebrum. These locations are consistent with sources observed in neuromagnetic studies of the human visual response.

  14. A generalized Fourier penalty in prior-image-based reconstruction for cross-platform imaging

    NASA Astrophysics Data System (ADS)

    Pourmorteza, A.; Siewerdsen, J. H.; Stayman, J. W.

    2016-03-01

    Sequential CT studies present an excellent opportunity to apply prior-image-based reconstruction (PIBR) methods that leverage high-fidelity prior imaging studies to improve image quality and/or reduce x-ray exposure in subsequent studies. One major obstacle in using PIBR is that the initial and subsequent studies are often performed on different scanners (e.g. diagnostic CT followed by CBCT for interventional guidance); this results in mismatch in attenuation values due to hardware and software differences. While improved artifact correction techniques can potentially mitigate such differences, the correction is often incomplete. Here, we present an alternate strategy where the PIBR itself is used to mitigate these differences. We define a new penalty for the previously introduced PIBR called Reconstruction of Difference (RoD). RoD differs from many other PIBRs in that it reconstructs only changes in the anatomy (vs. reconstructing the current anatomy). Direct regularization of the difference image in RoD provides an opportunity to selectively penalize spatial frequencies of the difference image (e.g. low frequency differences associated with attenuation offsets and shading artifacts) without interfering with the variations in unchanged background image. We leverage this flexibility and introduce a novel regularization strategy using a generalized Fourier penalty within the RoD framework and develop the modified reconstruction algorithm. We evaluate the performance of the new approach in both simulation studies and in physical CBCT test-bench data. We find that generalized Fourier penalty can be highly effective in reducing low-frequency x-ray artifacts through selective suppression of spatial frequencies in the reconstructed difference image.

  15. Automatic determination of the imaging plane in lumbar MRI

    NASA Astrophysics Data System (ADS)

    Masaki, Tsurumaki; Lee, Yongbum; Tsai, Du-Yih; Sekiya, Masaru; Kazama, Kiyoko

    2006-03-01

    In this paper we describe a method for assisting radiological technologists in their routine work to automatically determine the imaging plane in lumbar MRI. The method is first to recognize the spinal cord and the intervertebral disk (ID) from the lumbar vertebra 3-plane localizer image, and then the imaging plane is automatically determined according to the recognition results. To determine the imaging plane, the spinal cord and the ID are automatically recognized from the lumbar vertebra 3-plane localizer image with a series of image processing techniques. The proposed method consists of three major steps. First, after removing the air and fat regions from the 3-plane localizer image by use of histogram analysis, the rachis region is specified with Sobel edge detection filter. Second, the spinal cord and the ID were respectively extracted from the specified rachis region making use of global thresholding and the line detection filter. Finally, the imaging plane is determined by finding the straight line between the spinal cord and the ID with the Hough transform. Image data of 10 healthy volunteers were used for investigation. To validate the usefulness of our proposed method, manual determination of the imaging plane was also conducted by five experienced radiological technologists. Our experimental results showed that the concordance rate between the manual setting and automatic determination reached to 90%. Moreover, a remarkable reduction in execution time for imaging-plane determination was also achieved.

  16. 3D thermal medical image visualization tool: Integration between MRI and thermographic images.

    PubMed

    Abreu de Souza, Mauren; Chagas Paz, André Augusto; Sanches, Ionildo Jóse; Nohama, Percy; Gamba, Humberto Remigio

    2014-01-01

    Three-dimensional medical image reconstruction using different images modalities require registration techniques that are, in general, based on the stacking of 2D MRI/CT images slices. In this way, the integration of two different imaging modalities: anatomical (MRI/CT) and physiological information (infrared image), to generate a 3D thermal model, is a new methodology still under development. This paper presents a 3D THERMO interface that provides flexibility for the 3D visualization: it incorporates the DICOM parameters; different color scale palettes at the final 3D model; 3D visualization at different planes of sections; and a filtering option that provides better image visualization. To summarize, the 3D thermographc medical image visualization provides a realistic and precise medical tool. The merging of two different imaging modalities allows better quality and more fidelity, especially for medical applications in which the temperature changes are clinically significant.

  17. Whole-Body MRI in Children: Current Imaging Techniques and Clinical Applications

    PubMed Central

    2015-01-01

    Whole-body magnetic resonance imaging (MRI) is increasingly used in children to evaluate the extent and distribution of various neoplastic and non-neoplastic diseases. Not using ionizing radiation is a major advantage of pediatric whole-body MRI. Coronal and sagittal short tau inversion recovery imaging is most commonly used as the fundamental whole-body MRI protocol. Diffusion-weighted imaging and Dixon-based imaging, which has been recently incorporated into whole-body MRI, are promising pulse sequences, particularly for pediatric oncology. Other pulse sequences may be added to increase diagnostic capability of whole-body MRI. Of importance, the overall whole-body MRI examination time should be less than 30-60 minutes in children, regardless of the imaging protocol. Established and potentially useful clinical applications of pediatric whole-body MRI are described. PMID:26355493

  18. Nanomedicine strategies for molecular targets with MRI and optical imaging

    PubMed Central

    Pan, Dipanjan; Caruthers, Shelton D; Chen, Junjie; Winter, Patrick M; SenPan, Angana; Schmieder, Anne H; Wickline, Samuel A

    2010-01-01

    The science of ‘theranostics’ plays a crucial role in personalized medicine, which represents the future of patient management. Over the last decade an increasing research effort has focused on the development of nanoparticle-based molecular-imaging and drug-delivery approaches, emerging as a multidisciplinary field that shows promise in understanding the components, processes, dynamics and therapies of a disease at a molecular level. The potential of nanometer-sized agents for early detection, diagnosis and personalized treatment of diseases is extraordinary. They have found applications in almost all clinically relevant biomedical imaging modality. In this review, a number of these approaches will be presented with a particular emphasis on MRI and optical imaging-based techniques. We have discussed both established molecular-imaging approaches and recently developed innovative strategies, highlighting the seminal studies and a number of successful examples of theranostic nanomedicine, especially in the areas of cardiovascular and cancer therapy. PMID:20485473

  19. Improved compressed sensing-based cone-beam CT reconstruction using adaptive prior image constraints

    NASA Astrophysics Data System (ADS)

    Lee, Ho; Xing, Lei; Davidi, Ran; Li, Ruijiang; Qian, Jianguo; Lee, Rena

    2012-04-01

    Volumetric cone-beam CT (CBCT) images are acquired repeatedly during a course of radiation therapy and a natural question to ask is whether CBCT images obtained earlier in the process can be utilized as prior knowledge to reduce patient imaging dose in subsequent scans. The purpose of this work is to develop an adaptive prior image constrained compressed sensing (APICCS) method to solve this problem. Reconstructed images using full projections are taken on the first day of radiation therapy treatment and are used as prior images. The subsequent scans are acquired using a protocol of sparse projections. In the proposed APICCS algorithm, the prior images are utilized as an initial guess and are incorporated into the objective function in the compressed sensing (CS)-based iterative reconstruction process. Furthermore, the prior information is employed to detect any possible mismatched regions between the prior and current images for improved reconstruction. For this purpose, the prior images and the reconstructed images are classified into three anatomical regions: air, soft tissue and bone. Mismatched regions are identified by local differences of the corresponding groups in the two classified sets of images. A distance transformation is then introduced to convert the information into an adaptive voxel-dependent relaxation map. In constructing the relaxation map, the matched regions (unchanged anatomy) between the prior and current images are assigned with smaller weight values, which are translated into less influence on the CS iterative reconstruction process. On the other hand, the mismatched regions (changed anatomy) are associated with larger values and the regions are updated more by the new projection data, thus avoiding any possible adverse effects of prior images. The APICCS approach was systematically assessed by using patient data acquired under standard and low-dose protocols for qualitative and quantitative comparisons. The APICCS method provides an

  20. Imaging of acute stroke prior to treatment: current practice and evolving techniques

    PubMed Central

    Mair, G

    2014-01-01

    Standard imaging in acute stroke is undertaken with the aim of diagnosing the underlying cause and excluding stroke mimics. In the presence of ischaemic stroke, imaging is also needed to assess patient suitability for treatment with intravenous thrombolysis. Non-contrast CT is predominantly used, but MRI can also exclude any contraindications to thrombolysis treatment. Advanced stroke imaging such as CT and MR angiography and perfusion imaging are increasingly used in an acute setting. In this review, we discuss the evidence for the application of these advanced techniques in the imaging of acute stroke. PMID:24936980

  1. [Imaging procedures prior to the extracorporeal shockwave lithotripsy of gallstones].

    PubMed

    Schneider, H T; Ell, C; Benninger, J; Theobaldy, S; Friedel, N; Rödl, W; Heyder, N; Hahn, E G

    1991-01-25

    In order to determine whether cholecystography and computed tomography (CT) are capable of better gallstone characterization than conventional radiography alone, 91 patients (76 females, 15 males; mean age 47 +/- 12 years) with symptomatic single gallstones were studied prospectively prior to extracorporeal shock-wave lithotripsy with concomitant oral stone dissolution therapy. In addition, the value of oral cholecystography in demonstrating patency of the cystic duct was compared with ultrasound assessment of gallbladder function. Despite "negative" plain gallbladder radiographs in all patients, oral cholecystography showed significant stone calcification in 8 of the 91 patients and CT showed stone calcifications in 52 of the 91 patients. In 12 patients the maximum stone density was between 50 and 90 Hounsfield units, and in 40 patients it was more than 90 Hounsfield units. CT revealed ring-like calcification in the majority (79%) of these stones. Oral cholecystography showed satisfactory concentration of contrast medium in all patients, while ultrasonography of the gallbladder following a chemically defined test meal demonstrated contractility of more than 50% of initial volume in 69 patients and of less than 30% in 9 patients. Although oral cholecystography is a simple, readily available complication-free method, ultrasound assessment of gallbladder contraction is better for selecting patients for extracorporeal shock-wave lithotripsy. CT allows significantly better characterization of gallstones than oral cholecystography and conventional plain gallbladder radiography.

  2. Imaging of prostate cancer: a platform for 3D co-registration of in-vivo MRI ex-vivo MRI and pathology

    NASA Astrophysics Data System (ADS)

    Orczyk, Clément; Mikheev, Artem; Rosenkrantz, Andrew; Melamed, Jonathan; Taneja, Samir S.; Rusinek, Henry

    2012-02-01

    Objectives: Multi-parametric MRI is emerging as a promising method for prostate cancer diagnosis. prognosis and treatment planning. However, the localization of in-vivo detected lesions and pathologic sites of cancer remains a significant challenge. To overcome this limitation we have developed and tested a system for co-registration of in-vivo MRI, ex-vivo MRI and histology. Materials and Methods: Three men diagnosed with localized prostate cancer (ages 54-72, PSA levels 5.1-7.7 ng/ml) were prospectively enrolled in this study. All patients underwent 3T multi-parametric MRI that included T2W, DCEMRI, and DWI prior to robotic-assisted prostatectomy. Ex-vivo multi-parametric MRI was performed on fresh prostate specimen. Excised prostates were then sliced at regular intervals and photographed both before and after fixation. Slices were perpendicular to the main axis of the posterior capsule, i.e., along the direction of the rectal wall. Guided by the location of the urethra, 2D digital images were assembled into 3D models. Cancer foci, extra-capsular extensions and zonal margins were delineated by the pathologist and included in 3D histology data. A locally-developed software was applied to register in-vivo, ex-vivo and histology using an over-determined set of anatomical landmarks placed in anterior fibro-muscular stroma, central. transition and peripheral zones. The mean root square distance across corresponding control points was used to assess co-registration error. Results: Two specimens were pT3a and one pT2b (negative margin) at pathology. The software successfully fused invivo MRI. ex-vivo MRI fresh specimen and histology using appropriate (rigid and affine) transformation models with mean square error of 1.59 mm. Coregistration accuracy was confirmed by multi-modality viewing using operator-guided variable transparency. Conclusion: The method enables successful co-registration of pre-operative MRI, ex-vivo MRI and pathology and it provides initial evidence

  3. Multimodal MRI and cognitive function in patients with breast cancer prior to adjuvant treatment — The role of fatigue

    PubMed Central

    Menning, Sanne; de Ruiter, Michiel B.; Veltman, Dick J.; Koppelmans, V.; Kirschbaum, Clemens; Boogerd, Willem; Reneman, Liesbeth; Schagen, Sanne B.

    2015-01-01

    An increasing body of literature indicates that chemotherapy (ChT) for breast cancer (BC) is associated with adverse effects on the brain. Recent research suggests that cognitive and brain function in patients with BC may already be compromised before the start of chemotherapy. This is the first study combining neuropsychological testing, patient-reported outcomes, and multimodal magnetic resonance imaging (MRI) to examine pretreatment cognition and various aspects of brain function and structure in a large sample. Thirty-two patients with BC scheduled to receive ChT (pre-ChT+), 33 patients with BC not indicated to undergo ChT (pre-ChT−), and 38 no-cancer controls (NCs) were included. The examination consisted of a neuropsychological test battery, self-reported aspects of psychosocial functioning, and multimodal MRI. Patients with BC reported worse scores on several aspects of quality of life, such as higher levels of fatigue and stress. However, cortisol levels were not elevated in the patient groups compared to the control group. Overall cognitive performance was lower in the pre-ChT+ and the pre-ChT− groups compared to NC. Further, patients demonstrated prefrontal hyperactivation with increasing task difficulty on a planning task compared to NC, but not during a memory task. White matter integrity was lower in both patient groups. No differences in regional brain volume and brain metabolites were found. The cognitive and imaging data converged to show that symptoms of fatigue were associated with the observed abnormalities; the observed differences were no longer significant when fatigue was accounted for. This study suggests that cancer-related psychological or biological processes may adversely impact cognitive functioning and associated aspects of brain structure and function before the start of adjuvant treatment. Our findings stress the importance to further explore the processes underlying the expression of fatigue and to study whether it has a

  4. CNS Animal fMRI imaging in Pain and Analgesia

    PubMed Central

    Borsook, David; Becerra, Lino

    2010-01-01

    Animal imaging of brain systems offers exciting opportunities to better understand the neurobiology of pain and analgesia. Overall functional studies have lagged behind human studies as a result of technical issues including the use of anesthesia. Now that many of these issues have been overcome including the possibility of imaging awake animals, there are new opportunities to study whole brain systems neurobiology of acute and chronic pain as well as analgesic effects on brain systems de novo (using pharmacological MRI) or testing in animal models of pain. Understanding brain networks in these areas may provide new insights into translational science, and use neural networks as a “language of translation” between preclinical to clinical models. In this review we evaluate the role of functional and anatomical imaging in furthering our understanding in pain and analgesia. PMID:21126534

  5. Imaging of juvenile idiopathic arthritis. Part II: Ultrasonography and MRI

    PubMed Central

    Grochowska, Elżbieta; Gietka, Piotr; Płaza, Mateusz; Pracoń, Grzegorz; Saied, Fadhil; Walentowska-Janowicz, Marta

    2016-01-01

    Juvenile idiopathic arthritis is the most common autoimmune systemic disease of the connective tissue affecting individuals in the developmental age. Radiography, which was described in the first part of this publication, is the standard modality in the assessment of this condition. Ultrasound and magnetic resonance imaging enable early detection of the disease which affects soft tissues, as well as bones. Ultrasound assessment involves: joint cavities, tendon sheaths and bursae for the presence of synovitis, intraand extraarticular fat tissue to visualize signs of inflammation, hyaline cartilage, cartilaginous epiphysis and subchondral bone to detect cysts and erosions, and ligaments, tendons and their entheses for signs of enthesopathies and tendinopathies. Magnetic resonance imaging is indicated in children with juvenile idiopathic arthritis for assessment of inflammation in peripheral joints, tendon sheaths and bursae, bone marrow involvement and identification of inflammatory lesions in whole-body MRI, particularly when the clinical picture is unclear. Also, MRI of the spine and spinal cord is used in order to diagnose synovial joint inflammation, bone marrow edema and spondylodiscitis as well as to assess their activity, location, and complications (spinal canal stenosis, subluxation, e.g. in the atlantoaxial region). This article discusses typical pathological changes seen on ultrasound and magnetic resonance imaging. The role of these two methods for disease monitoring, its identification in the pre-clinical stage and establishing its remission are also highlighted. PMID:27679727

  6. Imaging of juvenile idiopathic arthritis. Part II: Ultrasonography and MRI.

    PubMed

    Sudoł-Szopińska, Iwona; Grochowska, Elżbieta; Gietka, Piotr; Płaza, Mateusz; Pracoń, Grzegorz; Saied, Fadhil; Walentowska-Janowicz, Marta

    2016-09-01

    Juvenile idiopathic arthritis is the most common autoimmune systemic disease of the connective tissue affecting individuals in the developmental age. Radiography, which was described in the first part of this publication, is the standard modality in the assessment of this condition. Ultrasound and magnetic resonance imaging enable early detection of the disease which affects soft tissues, as well as bones. Ultrasound assessment involves: joint cavities, tendon sheaths and bursae for the presence of synovitis, intraand extraarticular fat tissue to visualize signs of inflammation, hyaline cartilage, cartilaginous epiphysis and subchondral bone to detect cysts and erosions, and ligaments, tendons and their entheses for signs of enthesopathies and tendinopathies. Magnetic resonance imaging is indicated in children with juvenile idiopathic arthritis for assessment of inflammation in peripheral joints, tendon sheaths and bursae, bone marrow involvement and identification of inflammatory lesions in whole-body MRI, particularly when the clinical picture is unclear. Also, MRI of the spine and spinal cord is used in order to diagnose synovial joint inflammation, bone marrow edema and spondylodiscitis as well as to assess their activity, location, and complications (spinal canal stenosis, subluxation, e.g. in the atlantoaxial region). This article discusses typical pathological changes seen on ultrasound and magnetic resonance imaging. The role of these two methods for disease monitoring, its identification in the pre-clinical stage and establishing its remission are also highlighted.

  7. Imaging of juvenile idiopathic arthritis. Part II: Ultrasonography and MRI.

    PubMed

    Sudoł-Szopińska, Iwona; Grochowska, Elżbieta; Gietka, Piotr; Płaza, Mateusz; Pracoń, Grzegorz; Saied, Fadhil; Walentowska-Janowicz, Marta

    2016-09-01

    Juvenile idiopathic arthritis is the most common autoimmune systemic disease of the connective tissue affecting individuals in the developmental age. Radiography, which was described in the first part of this publication, is the standard modality in the assessment of this condition. Ultrasound and magnetic resonance imaging enable early detection of the disease which affects soft tissues, as well as bones. Ultrasound assessment involves: joint cavities, tendon sheaths and bursae for the presence of synovitis, intraand extraarticular fat tissue to visualize signs of inflammation, hyaline cartilage, cartilaginous epiphysis and subchondral bone to detect cysts and erosions, and ligaments, tendons and their entheses for signs of enthesopathies and tendinopathies. Magnetic resonance imaging is indicated in children with juvenile idiopathic arthritis for assessment of inflammation in peripheral joints, tendon sheaths and bursae, bone marrow involvement and identification of inflammatory lesions in whole-body MRI, particularly when the clinical picture is unclear. Also, MRI of the spine and spinal cord is used in order to diagnose synovial joint inflammation, bone marrow edema and spondylodiscitis as well as to assess their activity, location, and complications (spinal canal stenosis, subluxation, e.g. in the atlantoaxial region). This article discusses typical pathological changes seen on ultrasound and magnetic resonance imaging. The role of these two methods for disease monitoring, its identification in the pre-clinical stage and establishing its remission are also highlighted. PMID:27679727

  8. Imaging of juvenile idiopathic arthritis. Part II: Ultrasonography and MRI

    PubMed Central

    Grochowska, Elżbieta; Gietka, Piotr; Płaza, Mateusz; Pracoń, Grzegorz; Saied, Fadhil; Walentowska-Janowicz, Marta

    2016-01-01

    Juvenile idiopathic arthritis is the most common autoimmune systemic disease of the connective tissue affecting individuals in the developmental age. Radiography, which was described in the first part of this publication, is the standard modality in the assessment of this condition. Ultrasound and magnetic resonance imaging enable early detection of the disease which affects soft tissues, as well as bones. Ultrasound assessment involves: joint cavities, tendon sheaths and bursae for the presence of synovitis, intraand extraarticular fat tissue to visualize signs of inflammation, hyaline cartilage, cartilaginous epiphysis and subchondral bone to detect cysts and erosions, and ligaments, tendons and their entheses for signs of enthesopathies and tendinopathies. Magnetic resonance imaging is indicated in children with juvenile idiopathic arthritis for assessment of inflammation in peripheral joints, tendon sheaths and bursae, bone marrow involvement and identification of inflammatory lesions in whole-body MRI, particularly when the clinical picture is unclear. Also, MRI of the spine and spinal cord is used in order to diagnose synovial joint inflammation, bone marrow edema and spondylodiscitis as well as to assess their activity, location, and complications (spinal canal stenosis, subluxation, e.g. in the atlantoaxial region). This article discusses typical pathological changes seen on ultrasound and magnetic resonance imaging. The role of these two methods for disease monitoring, its identification in the pre-clinical stage and establishing its remission are also highlighted.

  9. Regularized image reconstruction algorithms for dual-isotope myocardial perfusion SPECT (MPS) imaging using a cross-tracer prior.

    PubMed

    He, Xin; Cheng, Lishui; Fessler, Jeffrey A; Frey, Eric C

    2011-06-01

    In simultaneous dual-isotope myocardial perfusion SPECT (MPS) imaging, data are simultaneously acquired to determine the distributions of two radioactive isotopes. The goal of this work was to develop penalized maximum likelihood (PML) algorithms for a novel cross-tracer prior that exploits the fact that the two images reconstructed from simultaneous dual-isotope MPS projection data are perfectly registered in space. We first formulated the simultaneous dual-isotope MPS reconstruction problem as a joint estimation problem. A cross-tracer prior that couples voxel values on both images was then proposed. We developed an iterative algorithm to reconstruct the MPS images that converges to the maximum a posteriori solution for this prior based on separable surrogate functions. To accelerate the convergence, we developed a fast algorithm for the cross-tracer prior based on the complete data OS-EM (COSEM) framework. The proposed algorithm was compared qualitatively and quantitatively to a single-tracer version of the prior that did not include the cross-tracer term. Quantitative evaluations included comparisons of mean and standard deviation images as well as assessment of image fidelity using the mean square error. We also evaluated the cross tracer prior using a three-class observer study with respect to the three-class MPS diagnostic task, i.e., classifying patients as having either no defect, reversible defect, or fixed defects. For this study, a comparison with conventional ordered subsets-expectation maximization (OS-EM) reconstruction with postfiltering was performed. The comparisons to the single-tracer prior demonstrated similar resolution for areas of the image with large intensity changes and reduced noise in uniform regions. The cross-tracer prior was also superior to the single-tracer version in terms of restoring image fidelity. Results of the three-class observer study showed that the proposed cross-tracer prior and the convergent algorithms improved the

  10. Automated identification of brain tumors from single MR images based on segmentation with refined patient-specific priors

    PubMed Central

    Sanjuán, Ana; Price, Cathy J.; Mancini, Laura; Josse, Goulven; Grogan, Alice; Yamamoto, Adam K.; Geva, Sharon; Leff, Alex P.; Yousry, Tarek A.; Seghier, Mohamed L.

    2013-01-01

    Brain tumors can have different shapes or locations, making their identification very challenging. In functional MRI, it is not unusual that patients have only one anatomical image due to time and financial constraints. Here, we provide a modified automatic lesion identification (ALI) procedure which enables brain tumor identification from single MR images. Our method rests on (A) a modified segmentation-normalization procedure with an explicit “extra prior” for the tumor and (B) an outlier detection procedure for abnormal voxel (i.e., tumor) classification. To minimize tissue misclassification, the segmentation-normalization procedure requires prior information of the tumor location and extent. We therefore propose that ALI is run iteratively so that the output of Step B is used as a patient-specific prior in Step A. We test this procedure on real T1-weighted images from 18 patients, and the results were validated in comparison to two independent observers' manual tracings. The automated procedure identified the tumors successfully with an excellent agreement with the manual segmentation (area under the ROC curve = 0.97 ± 0.03). The proposed procedure increases the flexibility and robustness of the ALI tool and will be particularly useful for lesion-behavior mapping studies, or when lesion identification and/or spatial normalization are problematic. PMID:24381535

  11. Edge-oriented dual-dictionary guided enrichment (EDGE) for MRI-CT image reconstruction.

    PubMed

    Li, Liang; Wang, Bigong; Wang, Ge

    2016-01-01

    In this paper, we formulate the joint/simultaneous X-ray CT and MRI image reconstruction. In particular, a novel algorithm is proposed for MRI image reconstruction from highly under-sampled MRI data and CT images. It consists of two steps. First, a training dataset is generated from a series of well-registered MRI and CT images on the same patients. Then, an initial MRI image of a patient can be reconstructed via edge-oriented dual-dictionary guided enrichment (EDGE) based on the training dataset and a CT image of the patient. Second, an MRI image is reconstructed using the dictionary learning (DL) algorithm from highly under-sampled k-space data and the initial MRI image. Our algorithm can establish a one-to-one correspondence between the two imaging modalities, and obtain a good initial MRI estimation. Both noise-free and noisy simulation studies were performed to evaluate and validate the proposed algorithm. The results with different under-sampling factors show that the proposed algorithm performed significantly better than those reconstructed using the DL algorithm from MRI data alone.

  12. Shape based MRI prostate image segmentation using local information driven directional distance Bayesian method

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Tannenbaum, Allen

    2010-03-01

    In this paper, we present a shape based segmentation methodology for magnetic resonance prostate images. We first propose a new way to represent shapes via the hyperbolic tangent of the signed distance function. This effectively corrects the drawbacks of the signed distance function and yields very reasonable results for the shape registration and learning. Secondly, under a Bayesian statistical framework, instead of computing the posterior using a uniform prior, a directional distance map is introduced in order to incorporate a priori knowledge of image content as well as the estimated center of target object. Essentially, the image is modeled as a Finsler manifold and the metric is computed out of the directional derivative of the image. Then the directional distance map is computed to suppress the posterior remote from the object center. Thirdly, in the posterior image, a localized region based cost functional is designed to drive the shape based segmentation. Such cost functional utilizes the local regional information and is robust to both image noise and remote/irrelevant disturbances. With these three major components, the entire shape based segmentation procedure is provided as a complete open source pipeline and is applied to magnetic resonance image (MRI) prostate data.

  13. Joint Prior Learning for Visual Sensor Network Noisy Image Super-Resolution

    PubMed Central

    Yue, Bo; Wang, Shuang; Liang, Xuefeng; Jiao, Licheng; Xu, Caijin

    2016-01-01

    The visual sensor network (VSN), a new type of wireless sensor network composed of low-cost wireless camera nodes, is being applied for numerous complex visual analyses in wild environments, such as visual surveillance, object recognition, etc. However, the captured images/videos are often low resolution with noise. Such visual data cannot be directly delivered to the advanced visual analysis. In this paper, we propose a joint-prior image super-resolution (JPISR) method using expectation maximization (EM) algorithm to improve VSN image quality. Unlike conventional methods that only focus on upscaling images, JPISR alternatively solves upscaling mapping and denoising in the E-step and M-step. To meet the requirement of the M-step, we introduce a novel non-local group-sparsity image filtering method to learn the explicit prior and induce the geometric duality between images to learn the implicit prior. The EM algorithm inherently combines the explicit prior and implicit prior by joint learning. Moreover, JPISR does not rely on large external datasets for training, which is much more practical in a VSN. Extensive experiments show that JPISR outperforms five state-of-the-art methods in terms of both PSNR, SSIM and visual perception. PMID:26927114

  14. Joint Prior Learning for Visual Sensor Network Noisy Image Super-Resolution.

    PubMed

    Yue, Bo; Wang, Shuang; Liang, Xuefeng; Jiao, Licheng; Xu, Caijin

    2016-01-01

    The visual sensor network (VSN), a new type of wireless sensor network composed of low-cost wireless camera nodes, is being applied for numerous complex visual analyses in wild environments, such as visual surveillance, object recognition, etc. However, the captured images/videos are often low resolution with noise. Such visual data cannot be directly delivered to the advanced visual analysis. In this paper, we propose a joint-prior image super-resolution (JPISR) method using expectation maximization (EM) algorithm to improve VSN image quality. Unlike conventional methods that only focus on upscaling images, JPISR alternatively solves upscaling mapping and denoising in the E-step and M-step. To meet the requirement of the M-step, we introduce a novel non-local group-sparsity image filtering method to learn the explicit prior and induce the geometric duality between images to learn the implicit prior. The EM algorithm inherently combines the explicit prior and implicit prior by joint learning. Moreover, JPISR does not rely on large external datasets for training, which is much more practical in a VSN. Extensive experiments show that JPISR outperforms five state-of-the-art methods in terms of both PSNR, SSIM and visual perception. PMID:26927114

  15. Clinical Utility of Positron Emission Tomography Magnetic Resonance Imaging (PET-MRI) in Gastrointestinal Cancers.

    PubMed

    Matthews, Robert; Choi, Minsig

    2016-01-01

    Anatomic imaging utilizing both CT (computed tomography) and MRI (magnetic resonance imaging) limits the assessment of cancer metastases in lymph nodes and distant organs while functional imaging like PET (positron emission tomography) scan has its limitation in spatial resolution capacity. Hybrid imaging utilizing PET-CT and PET-MRI are novel imaging modalities that are changing the current landscape in cancer diagnosis, staging, and treatment response. MRI has shown to have higher sensitivity in soft tissue, head and neck pathology, and pelvic disease, as well as, detecting small metastases in the liver and bone compared to CT. Combining MRI with PET allows for detection of metastases that may have been missed with current imaging modalities. In this review, we will examine the clinical utility of FDG PET-MRI in the diagnosis and staging of gastrointestinal cancers with focus on esophageal, stomach, colorectal, and pancreatic cancers. We will also explore its role in treatment response and future directions associated with it.

  16. [Research progress of techniques of 7 T MRI system in brain imaging].

    PubMed

    Lin, Lan; Hao, Dongmei; Bai, Yanping; Gao, Hongjian; Wu, Shuicai

    2013-10-01

    7 T high field magnetic resonance imaging (MRI) provides a useful tool for microscopic spatial resolution visualizing anatomy. In addition, it enables the observation and analysis of tissue metabolism and function. 7 T MRI is now developing fast both in its technology and in its potential prospective medical applications. This review introduces current applications and possible future developments of the 7 T MRI in the field of human brain imaging for clinical studies and practices.

  17. Radar coincidence imaging with phase error using Bayesian hierarchical prior modeling

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoli; Wang, Hongqiang; Cheng, Yongqiang; Qin, Yuliang

    2016-01-01

    Radar coincidence imaging (RCI) is a high-resolution imaging technique without the limitation of relative motion between target and radar. In sparsity-driven RCI, the prior knowledge of imaging model requires to be known accurately. However, the phase error generally exists as a model error, which may cause inaccuracies of the model and defocus the image. The problem is formulated using Bayesian hierarchical prior modeling, and the self-calibration variational message passing (SC-VMP) algorithm is proposed to improve the performance of RCI with phase error. The algorithm determines the phase error as part of the imaging process. The scattering coefficient and phase error are iteratively estimated using VMP and Newton's method, respectively. Simulation results show that the proposed algorithm can estimate the phase error accurately and improve the imaging quality significantly.

  18. Super-resolution of hyperspectral images using sparse representation and Gabor prior

    NASA Astrophysics Data System (ADS)

    Patel, Rakesh C.; Joshi, Manjunath V.

    2016-04-01

    Super-resolution (SR) as a postprocessing technique is quite useful in enhancing the spatial resolution of hyperspectral (HS) images without affecting its spectral resolution. We present an approach to increase the spatial resolution of HS images by making use of sparse representation and Gabor prior. The low-resolution HS observations consisting of large number of bands are represented as a linear combination of a small number of basis images using principal component analysis (PCA), and the significant components are used in our work. We first obtain initial estimates of SR on this reduced dimension by using compressive sensing-based method. Since SR is an ill-posed problem, the final solution is obtained by using a regularization framework. The novelty of our approach lies in: (1) estimation of optimal point spread function in the form of decimation matrix, and (2) using a new prior called "Gabor prior" to super-resolve the significant PCA components. Experiments are conducted on two different HS datasets namely, 31-band natural HS image set collected under controlled laboratory environment and a set of 224-band real HS images collected by airborne visible/infrared imaging spectrometer remote sensing sensor. Visual inspections and quantitative comparison confirm that our method enhances spatial information without introducing significant spectral distortion. Our conclusions include: (1) incorporate the sensor characteristics in the form of estimated decimation matrix for SR, and (2) preserve various frequencies in super-resolved image by making use of Gabor prior.

  19. TH-A-BRF-08: Deformable Registration of MRI and CT Images for MRI-Guided Radiation Therapy

    SciTech Connect

    Zhong, H; Wen, N; Gordon, J; Movsas, B; Chetty, I

    2014-06-15

    Purpose: To evaluate the quality of a commercially available MRI-CT image registration algorithm and then develop a method to improve the performance of this algorithm for MRI-guided prostate radiotherapy. Methods: Prostate contours were delineated on ten pairs of MRI and CT images using Eclipse. Each pair of MRI and CT images was registered with an intensity-based B-spline algorithm implemented in Velocity. A rectangular prism that contains the prostate volume was partitioned into a tetrahedral mesh which was aligned to the CT image. A finite element method (FEM) was developed on the mesh with the boundary constraints assigned from the Velocity generated displacement vector field (DVF). The resultant FEM displacements were used to adjust the Velocity DVF within the prism. Point correspondences between the CT and MR images identified within the prism could be used as additional boundary constraints to enforce the model deformation. The FEM deformation field is smooth in the interior of the prism, and equal to the Velocity displacements at the boundary of the prism. To evaluate the Velocity and FEM registration results, three criteria were used: prostate volume conservation and center consistence under contour mapping, and unbalanced energy of their deformation maps. Results: With the DVFs generated by the Velocity and FEM simulations, the prostate contours were warped from MRI to CT images. With the Velocity DVFs, the prostate volumes changed 10.2% on average, in contrast to 1.8% induced by the FEM DVFs. The average of the center deviations was 0.36 and 0.27 cm, and the unbalance energy was 2.65 and 0.38 mJ/cc3 for the Velocity and FEM registrations, respectively. Conclusion: The adaptive FEM method developed can be used to reduce the error of the MIbased registration algorithm implemented in Velocity in the prostate region, and consequently may help improve the quality of MRI-guided radiation therapy.

  20. A Novel Technique to Improve Photometry in Confused Images Using Graphs and Bayesian Priors

    NASA Astrophysics Data System (ADS)

    Safarzadeh, Mohammadtaher; Ferguson, Henry C.; Lu, Yu; Inami, Hanae; Somerville, Rachel S.

    2015-01-01

    We present a new technique for overcoming confusion noise in deep far-infrared Herschel space telescope images making use of prior information from shorter λ < 2 μm wavelengths. For the deepest images obtained by Herschel, the flux limit due to source confusion is about a factor of three brighter than the flux limit due to instrumental noise and (smooth) sky background. We have investigated the possibility of de-confusing simulated Herschel PACS 160 μm images by using strong Bayesian priors on the positions and weak priors on the flux of sources. We find the blended sources and group them together and simultaneously fit their fluxes. We derive the posterior probability distribution function of fluxes subject to these priors through Monte Carlo Markov Chain (MCMC) sampling by fitting the image. Assuming we can predict the FIR flux of sources based on the ultraviolet-optical part of their SEDs to within an order of magnitude, the simulations show that we can obtain reliable fluxes and uncertainties at least a factor of three fainter than the confusion noise limit of 3σ c = 2.7 mJy in our simulated PACS-160 image. This technique could in principle be used to mitigate the effects of source confusion in any situation where one has prior information of positions and plausible fluxes of blended sources. For Herschel, application of this technique will improve our ability to constrain the dust content in normal galaxies at high redshift.

  1. A NOVEL TECHNIQUE TO IMPROVE PHOTOMETRY IN CONFUSED IMAGES USING GRAPHS AND BAYESIAN PRIORS

    SciTech Connect

    Safarzadeh, Mohammadtaher; Ferguson, Henry C.; Lu, Yu; Inami, Hanae; Somerville, Rachel S.

    2015-01-10

    We present a new technique for overcoming confusion noise in deep far-infrared Herschel space telescope images making use of prior information from shorter λ < 2 μm wavelengths. For the deepest images obtained by Herschel, the flux limit due to source confusion is about a factor of three brighter than the flux limit due to instrumental noise and (smooth) sky background. We have investigated the possibility of de-confusing simulated Herschel PACS 160 μm images by using strong Bayesian priors on the positions and weak priors on the flux of sources. We find the blended sources and group them together and simultaneously fit their fluxes. We derive the posterior probability distribution function of fluxes subject to these priors through Monte Carlo Markov Chain (MCMC) sampling by fitting the image. Assuming we can predict the FIR flux of sources based on the ultraviolet-optical part of their SEDs to within an order of magnitude, the simulations show that we can obtain reliable fluxes and uncertainties at least a factor of three fainter than the confusion noise limit of 3σ {sub c} = 2.7 mJy in our simulated PACS-160 image. This technique could in principle be used to mitigate the effects of source confusion in any situation where one has prior information of positions and plausible fluxes of blended sources. For Herschel, application of this technique will improve our ability to constrain the dust content in normal galaxies at high redshift.

  2. Feasibility of an intracranial EEG-fMRI protocol at 3T: risk assessment and image quality.

    PubMed

    Boucousis, Shannon M; Beers, Craig A; Cunningham, Cameron J B; Gaxiola-Valdez, Ismael; Pittman, Daniel J; Goodyear, Bradley G; Federico, Paolo

    2012-11-15

    Integrating intracranial EEG (iEEG) with functional MRI (iEEG-fMRI) may help elucidate mechanisms underlying the generation of seizures. However, the introduction of iEEG electrodes in the MR environment has inherent risk and data quality implications that require consideration prior to clinical use. Previous studies of subdural and depth electrodes have confirmed low risk under specific circumstances at 1.5T and 3T. However, no studies have assessed risk and image quality related to the feasibility of a full iEEG-fMRI protocol. To this end, commercially available platinum subdural grid/strip electrodes (4×5 grid or 1×8 strip) and 4 or 6-contact depth electrodes were secured to the surface of a custom-made phantom mimicking the conductivity of the human brain. Electrode displacement, temperature increase of electrodes and surrounding phantom material, and voltage fluctuations in electrode contacts were measured in a GE Discovery MR750 3T MR scanner during a variety of imaging sequences, typical of an iEEG-fMRI protocol. An electrode grid was also used to quantify the spatial extent of susceptibility artifact. The spatial extent of susceptibility artifact in the presence of an electrode was also assessed for typical imaging parameters that maximize BOLD sensitivity at 3T (TR=1500 ms; TE=30 ms; slice thickness=4mm; matrix=64×64; field-of-view=24 cm). Under standard conditions, all electrodes exhibited no measurable displacement and no clinically significant temperature increase (<1°C) during scans employed in a typical iEEG-fMRI experiment, including 60 min of continuous fMRI. However, high SAR sequences, such as fast spin-echo (FSE), produced significant heating in almost all scenarios (>2.0°C) that in some cases exceeded 10°C. Induced voltages in the frequency range that could elicit neuronal stimulation (<10 kHz) were well below the threshold of 100 mV. fMRI signal intensity was significantly reduced within 20mm of the electrodes for the imaging parameters

  3. Testing the quality of images for permanent magnet desktop MRI systems using specially designed phantoms

    NASA Astrophysics Data System (ADS)

    Qiu, Jianfeng; Wang, Guozhu; Min, Jiao; Wang, Xiaoyan; Wang, Pengcheng

    2013-12-01

    Our aim was to measure the performance of desktop magnetic resonance imaging (MRI) systems using specially designed phantoms, by testing imaging parameters and analysing the imaging quality. We designed multifunction phantoms with diameters of 18 and 60 mm for desktop MRI scanners in accordance with the American Association of Physicists in Medicine (AAPM) report no. 28. We scanned the phantoms with three permanent magnet 0.5 T desktop MRI systems, measured the MRI image parameters, and analysed imaging quality by comparing the data with the AAPM criteria and Chinese national standards. Image parameters included: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, signal-to-noise ratio (SNR), and image uniformity. The image parameters of three desktop MRI machines could be measured using our specially designed phantoms, and most parameters were in line with MRI quality control criterion, including: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, image uniformity and slice position accuracy. However, SNR was significantly lower than in some references. The imaging test and quality control are necessary for desktop MRI systems, and should be performed with the applicable phantom and corresponding standards.

  4. Constructing a prior information base for river mapping from digital images and DEMs by an advanced image interpretation system

    NASA Astrophysics Data System (ADS)

    Demirkesen, Ali Can

    The purpose of this dissertation is to describe the construction of a prior information-base (interpretation of river characteristics) for river mapping from digital representations, such as remotely sensed digital images and DEMs, by an advanced image interpretation system. More reliable prior information availability in an advanced image interpretation system enables GIS and remote sensing facilities to locate rivers in an easier, more accurate and more straightforward way. In this study, the author proposes a prior information-base including some rules and facts for river mapping from the use of both remotely sensed multi-spectral images and DEMs. These rules not only allow water-related applications in both GIS and remote sensing to be more accurate, but also construct the information-base for river mapping by an advanced image interpretation system. These rules were constructed as a synthesis from searching the literature and experiments with both digital images and DEMs. These rules are employed in an advanced image interpretation system which requires (1) a prior information-base; (2) a working memory; (3) an inference module (Caelli and Bischof, 1997; Schenk and Zilberstein, 1990). A prior information-base is formed by a set of rules (qualitative or quantitative or relationships). A working memory has the basic function of holding features in the form of spatial data and their attribute values. These spatial and attribute data are used by interpreters to activate the rules. Inference module refers to software and hardware that connect the user's questions to the prior information-base and instruct the user (interpreter) about the process. In this dissertation, a prior information-based river mapping was implemented and the proposed rules were tested studying both images and DEMs in IDRISI, as well as RiverTools.

  5. Design of a Novel MRI Compatible Manipulator for Image Guided Prostate Interventions

    PubMed Central

    Krieger, Axel; Susil, Robert C.; Ménard, Cynthia; Coleman, Jonathan A.; Fichtinger, Gabor; Atalar, Ergin

    2012-01-01

    This paper reports a novel remotely actuated manipulator for access to prostate tissue under magnetic resonance imaging guidance (APT-MRI) device, designed for use in a standard high-field MRI scanner. The device provides three-dimensional MRI guided needle placement with millimeter accuracy under physician control. Procedures enabled by this device include MRI guided needle biopsy, fiducial marker placements, and therapy delivery. Its compact size allows for use in both standard cylindrical and open configuration MRI scanners. Preliminary in vivo canine experiments and first clinical trials are reported. PMID:15709668

  6. Amyloid imaging using fluorine-19 magnetic resonance imaging ((19)F-MRI).

    PubMed

    Tooyama, Ikuo; Yanagisawa, Daijiro; Taguchi, Hiroyasu; Kato, Tomoko; Hirao, Koichi; Shirai, Nobuaki; Sogabe, Takayuki; Ibrahim, Nor Faeizah; Inubushi, Toshiro; Morikawa, Shigehiro

    2016-09-01

    The formation of senile plaques followed by the deposition of amyloid-β is the earliest pathological change in Alzheimer's disease. Thus, the detection of senile plaques remains the most important early diagnostic indicator of Alzheimer's disease. Amyloid imaging is a noninvasive technique for visualizing senile plaques in the brains of Alzheimer's patients using positron emission tomography (PET) or magnetic resonance imaging (MRI). Because fluorine-19 ((19)F) displays an intense nuclear magnetic resonance signal and is almost non-existent in the body, targets are detected with a higher signal-to-noise ratio using appropriate fluorinated contrast agents. The recent introduction of high-field MRI allows us to detect amyloid depositions in the brain of living mouse using (19)F-MRI. So far, at least three probes have been reported to detect amyloid deposition in the brain of transgenic mouse models of Alzheimer's disease; (E,E)-1-fluoro-2,5-bis-(3-hydroxycarbonyl-4-hydroxy)styrylbenzene (FSB), 1,7-bis(4'-hydroxy-3'-trifluoromethoxyphenyl)-4-methoxycarbonylethyl-1,6-heptadiene3,5-dione (FMeC1, Shiga-Y5) and 6-(3',6',9',15',18',21'-heptaoxa-23',23',23'-trifluorotricosanyloxy)-2-(4'-dimethylaminostyryl)benzoxazole (XP7, Shiga-X22). This review presents the recent advances in amyloid imaging using (19)F-MRI, including our own studies.

  7. A Fast Single Image Haze Removal Algorithm Using Color Attenuation Prior.

    PubMed

    Zhu, Qingsong; Mai, Jiaming; Shao, Ling

    2015-11-01

    Single image haze removal has been a challenging problem due to its ill-posed nature. In this paper, we propose a simple but powerful color attenuation prior for haze removal from a single input hazy image. By creating a linear model for modeling the scene depth of the hazy image under this novel prior and learning the parameters of the model with a supervised learning method, the depth information can be well recovered. With the depth map of the hazy image, we can easily estimate the transmission and restore the scene radiance via the atmospheric scattering model, and thus effectively remove the haze from a single image. Experimental results show that the proposed approach outperforms state-of-the-art haze removal algorithms in terms of both efficiency and the dehazing effect.

  8. Implicit and explicit prior information in near-infrared spectral imaging: accuracy, quantification and diagnostic value

    PubMed Central

    Pogue, Brian W.; Davis, Scott C.; Leblond, Frederic; Mastanduno, Michael A.; Dehghani, Hamid; Paulsen, Keith D.

    2011-01-01

    Near-infrared spectroscopy (NIRS) of tissue provides quantification of absorbers, scattering and luminescent agents in bulk tissue through the use of measurement data and assumptions. Prior knowledge can be critical about things such as (i) the tissue shape and/or structure, (ii) spectral constituents, (iii) limits on parameters, (iv) demographic or biomarker data, and (v) biophysical models of the temporal signal shapes. A general framework of NIRS imaging with prior information is presented, showing that prior information datasets could be incorporated at any step in the NIRS process, with the general workflow being: (i) data acquisition, (ii) pre-processing, (iii) forward model, (iv) inversion/reconstruction, (v) post-processing, and (vi) interpretation/diagnosis. Most of the development in NIRS has used ad hoc or empirical implementations of prior information such as pre-measured absorber or fluorophore spectra, or tissue shapes as estimated by additional imaging tools. A comprehensive analysis would examine what prior information maximizes the accuracy in recovery and value for medical diagnosis, when implemented at separate stages of the NIRS sequence. Individual applications of prior information can show increases in accuracy or improved ability to estimate biochemical features of tissue, while other approaches may not. Most beneficial inclusion of prior information has been in the inversion/reconstruction process, because it solves the mathematical intractability. However, it is not clear that this is always the most beneficial stage. PMID:22006905

  9. Unsupervised segmentation of MRI knees using image partition forests

    NASA Astrophysics Data System (ADS)

    Marčan, Marija; Voiculescu, Irina

    2016-03-01

    Nowadays many people are affected by arthritis, a condition of the joints with limited prevention measures, but with various options of treatment the most radical of which is surgical. In order for surgery to be successful, it can make use of careful analysis of patient-based models generated from medical images, usually by manual segmentation. In this work we show how to automate the segmentation of a crucial and complex joint -- the knee. To achieve this goal we rely on our novel way of representing a 3D voxel volume as a hierarchical structure of partitions which we have named Image Partition Forest (IPF). The IPF contains several partition layers of increasing coarseness, with partitions nested across layers in the form of adjacency graphs. On the basis of a set of properties (size, mean intensity, coordinates) of each node in the IPF we classify nodes into different features. Values indicating whether or not any particular node belongs to the femur or tibia are assigned through node filtering and node-based region growing. So far we have evaluated our method on 15 MRI knee images. Our unsupervised segmentation compared against a hand-segmented gold standard has achieved an average Dice similarity coefficient of 0.95 for femur and 0.93 for tibia, and an average symmetric surface distance of 0.98 mm for femur and 0.73 mm for tibia. The paper also discusses ways to introduce stricter morphological and spatial conditioning in the bone labelling process.

  10. Image to physical space registration of supine breast MRI for image guided breast surgery

    NASA Astrophysics Data System (ADS)

    Conley, Rebekah H.; Meszoely, Ingrid M.; Pheiffer, Thomas S.; Weis, Jared A.; Yankeelov, Thomas E.; Miga, Michael I.

    2014-03-01

    Breast conservation therapy (BCT) is a desirable option for many women diagnosed with early stage breast cancer and involves a lumpectomy followed by radiotherapy. However, approximately 50% of eligible women will elect for mastectomy over BCT despite equal survival benefit (provided margins of excised tissue are cancer free) due to uncertainty in outcome with regards to complete excision of cancerous cells, risk of local recurrence, and cosmesis. Determining surgical margins intraoperatively is difficult and achieving negative margins is not as robust as it needs to be, resulting in high re-operation rates and often mastectomy. Magnetic resonance images (MRI) can provide detailed information about tumor margin extents, however diagnostic images are acquired in a fundamentally different patient presentation than that used in surgery. Therefore, the high quality diagnostic MRIs taken in the prone position with pendant breast are not optimal for use in surgical planning/guidance due to the drastic shape change between preoperative images and the common supine surgical position. This work proposes to investigate the value of supine MRI in an effort to localize tumors intraoperatively using image-guidance. Mock intraoperative setups (realistic patient positioning in non-sterile environment) and preoperative imaging data were collected from a patient scheduled for a lumpectomy. The mock intraoperative data included a tracked laser range scan of the patient's breast surface, tracked center points of MR visible fiducials on the patient's breast, and tracked B-mode ultrasound and strain images. The preoperative data included a supine MRI with visible fiducial markers. Fiducial markers localized in the MRI were rigidly registered to their mock intraoperative counterparts using an optically tracked stylus. The root mean square (RMS) fiducial registration error using the tracked markers was 3.4mm. Following registration, the average closest point distance between the MR

  11. MRI

    MedlinePlus

    MRI does not use ionizing radiation. No side effects from the magnetic fields and radio waves have been reported. The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions rarely ...

  12. Should routine MRI of the lumbar spine be required prior to lumbar epidural steroid injection for sciatica pain?

    PubMed Central

    Ghaly, Ramis F.; Lissounov, Alexei; Candido, Kenneth D.; Knezevic, Nebojsa Nick

    2015-01-01

    Background: We describe three patients who received lumbar epidural steroid injections (LESI) for lumbosacral radicular pain that resulted in worsening of their symptoms. The procedures were performed following a review of remote diagnostic imaging studies. These cases demonstrate the lack of consensus in pain management domains for how to approach the workup and treatment of persistent/chronic low back pain, with a noted fragmentation in pain management strategies and applied therapies. Case Description: We present three patients; two female patients (37 and 38 years old) undergoing LESI for remotely diagnosed disc herniations, and one 61-year-old male receiving an LESI for a presumed, unverified lumbar intervertebral disc disorder. Following a worsening of symptoms after LESI, neurosurgical consultations ultimately determined the presence of, respectively, an epidural hematoma, a neurilemoma, and a lung cancer metastasis to the sacrum as the source of symptoms, instead of being due to the intervertebral disc pathology. Conclusions: We would like to emphasize several principles in the diagnosis and use of imaging of the lumbosacral region prior to undertaking invasive neuraxial procedures. PMID:25883840

  13. Complementary aspects of diffusion imaging and fMRI; I: structure and function.

    PubMed

    Mulkern, Robert V; Davis, Peter E; Haker, Steven J; Estepar, Raul San Jose; Panych, Lawrence P; Maier, Stephan E; Rivkin, Michael J

    2006-05-01

    Studying the intersection of brain structure and function is an important aspect of modern neuroscience. The development of magnetic resonance imaging (MRI) over the last 25 years has provided new and powerful tools for the study of brain structure and function. Two tools in particular, diffusion imaging and functional MRI (fMRI), are playing increasingly important roles in elucidating the complementary aspects of brain structure and function. In this work, we review basic technical features of diffusion imaging and fMRI for studying the integrity of white matter structural components and for determining the location and extent of cortical activation in gray matter, respectively. We then review a growing body of literature in which the complementary aspects of diffusion imaging and fMRI, applied as separate examinations but analyzed in tandem, have been exploited to enhance our knowledge of brain structure and function. PMID:16677953

  14. Vision 20/20: Simultaneous CT-MRI — Next chapter of multimodality imaging

    SciTech Connect

    Wang, Ge Xi, Yan; Gjesteby, Lars; Getzin, Matthew; Yang, Qingsong; Cong, Wenxiang; Vannier, Michael

    2015-10-15

    Multimodality imaging systems such as positron emission tomography-computed tomography (PET-CT) and MRI-PET are widely available, but a simultaneous CT-MRI instrument has not been developed. Synergies between independent modalities, e.g., CT, MRI, and PET/SPECT can be realized with image registration, but such postprocessing suffers from registration errors that can be avoided with synchronized data acquisition. The clinical potential of simultaneous CT-MRI is significant, especially in cardiovascular and oncologic applications where studies of the vulnerable plaque, response to cancer therapy, and kinetic and dynamic mechanisms of targeted agents are limited by current imaging technologies. The rationale, feasibility, and realization of simultaneous CT-MRI are described in this perspective paper. The enabling technologies include interior tomography, unique gantry designs, open magnet and RF sequences, and source and detector adaptation. Based on the experience with PET-CT, PET-MRI, and MRI-LINAC instrumentation where hardware innovation and performance optimization were instrumental to construct commercial systems, the authors provide top-level concepts for simultaneous CT-MRI to meet clinical requirements and new challenges. Simultaneous CT-MRI fills a major gap of modality coupling and represents a key step toward the so-called “omnitomography” defined as the integration of all relevant imaging modalities for systems biology and precision medicine.

  15. Magnetic resonance imaging in interventional therapy of patients with acute myocardial infarction prior to and after treatment

    PubMed Central

    Li, Yuzhou; Li, Chunrong; Jin, Hongrui; Huang, Wenqi

    2016-01-01

    The aim of the study was to investigate the cardiac magnetic resonance (CMR) imaging in interventional therapy of patients with acute myocardial infarction prior to and after treatment. Fifty-six cases of AMI patients with elective treatment by percutaneous coronary intervention (PCI) were continuously selected. Patients with an incidence of 7–10 days were treated with CMR and echocardiography to evaluate the quality of myocardial infarction, visual score method (VSM), wall motion score abnormality, left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD) and left ventricular ejection fraction (LVEF). Patients with an incidence of 10–14 days were treated with PCI, and CMR and echocardiography were evaluated after 6 months, after which the occurrence of major adverse cardiac events (MACE) were compared. The infarction quality, VSM score and wall motion abnormality (WMA) score were significantly reduced following surgery, and the difference was statistically significant (P<0.05). Ultrasound evaluation of LVEDD, LVESD, and LVEF prior to and after surgery was compared, and the difference was not statistically significant (P>0.05). Evaluation of the magnetic resonance imaging (MRI) in LVEDD prior to surgery was increased compared with that of the ultrasound in LVEDD, whereas MRI in LVESD and LVEF was decreased compared to that of the ultrasound obtained for LVESD and LVEF. Additionally, postoperative LVEDD was reduced compared with preoperative LVEDD, whereas LVEF was increased, and the difference was statistically significant (P<0.05). However, the evaluation of LVESD using the two methods exhibited no significant change. MACE occurred in 7 (12.5%) of 56 cases. The infarction quality of patients in the MACE group following surgery indicated that VSM and WMA scores were significantly higher than the group without MACE, while LVEF was lower than the MACE group following surgery, and the difference was statistically significant

  16. Methods of and apparatus for recording images occurring just prior to a rapid, random event

    DOEpatents

    Kelley, Edward F.

    1994-01-01

    An apparatus and a method are disclosed for recording images of events in a medium wherein the images that are recorded are of conditions existing just prior to and during the occurrence of an event that triggers recording of these images. The apparatus and method use an optical delay path that employs a spherical focusing mirror facing a circular array of flat return mirrors around a central flat mirror. The image is reflected in a symmetric pattern which balances astigmatism which is created by the spherical mirror. Delays on the order of hundreds of nanoseconds are possible.

  17. Improving synthesis and analysis prior blind compressed sensing with low-rank constraints for dynamic MRI reconstruction.

    PubMed

    Majumdar, Angshul

    2015-01-01

    In blind compressed sensing (BCS), both the sparsifying dictionary and the sparse coefficients are estimated simultaneously during signal recovery. A recent study adopted the BCS framework for recovering dynamic MRI sequences from under-sampled K-space measurements; the results were promising. Previous works in dynamic MRI reconstruction showed that, recovery accuracy can be improved by incorporating low-rank penalties into the standard compressed sensing (CS) optimization framework. Our work is motivated by these studies, and we improve upon the basic BCS framework by incorporating low-rank penalties into the optimization problem. The resulting optimization problem has not been solved before; hence we derive a Split Bregman type technique to solve the same. Experiments were carried out on real dynamic contrast enhanced MRI sequences. Results show that, with our proposed improvement, the reconstruction accuracy is better than BCS and other state-of-the-art dynamic MRI recovery algorithms.

  18. Unsupervised segmentation of the prostate using MR images based on level set with a shape prior.

    PubMed

    Liu, Xin; Langer, D L; Haider, M A; Van der Kwast, T H; Evans, A J; Wernick, M N; Yetik, I S

    2009-01-01

    Prostate cancer is the second leading cause of cancer death in American men. Current prostate MRI can benefit from automated tumor localization to help guide biopsy, radiotherapy and surgical planning. An important step of automated prostate cancer localization is the segmentation of the prostate. In this paper, we propose a fully automatic method for the segmentation of the prostate. We firstly apply a deformable ellipse model to find an ellipse that best fits the prostate shape. Then, this ellipse is used to initiate the level set and constrain the level set evolution with a shape penalty term. Finally, certain post processing methods are applied to refine the prostate boundaries. We apply the proposed method to real diffusion-weighted (DWI) MRI images data to test the performance. Our results show that accurate segmentation can be obtained with the proposed method compared to human readers.

  19. A fluorescent, paramagnetic and PEGylated gold/silica nanoparticle for MRI, CT and fluorescence imaging

    PubMed Central

    van Schooneveld, Matti M.; Cormode, David P.; Koole, Rolf; van Wijngaarden, J. Timon; Calcagno, Claudia; Skajaa, Torjus; Hilhorst, Jan; ’t Hart, Dannis C.; Fayad, Zahi A.; Mulder, Willem J. M.; Meijerink, Andries

    2013-01-01

    An important challenge in medical diagnostics is to design all-in-one contrast agents that can be detected with multiple techniques such as magnetic resonance imaging (MRI), X-ray computed tomography (CT), positron emission tomography (PET), single photon emission tomography (SPECT) or fluorescence imaging (FI). Although many dual labeled agents have been proposed, mainly for combined MRI/FI, constructs for three imaging modalities are scarce. Here gold/silica nanoparticles with a poly(ethylene glycol), paramagnetic and fluorescent lipid coating were synthesized, characterized and applied as trimodal contrast agents to allow for nanoparticle-enhanced imaging of macrophage cells in vitro via MRI, CT and FI, and mice livers in vivo via MRI and CT. This agent can be a useful tool in a multitude of applications, including cell tracking and target-specific molecular imaging, and is a step in the direction of truly multi-modal imaging. PMID:20812290

  20. Pediatric whole-body MRI: A review of current imaging techniques and clinical applications.

    PubMed

    Davis, Joseph T; Kwatra, Neha; Schooler, Gary R

    2016-10-01

    There are many congenital, neoplastic, inflammatory, and infectious processes in the pediatric patient for which whole-body imaging may be of benefit diagnostically and prognostically. With recent improvements in magnetic resonance imaging (MRI) hardware and software and resultant dramatically reduced scan times, imaging of the whole body with MRI has become a much more practicable technique in children. Whole-body MRI can provide a high level of soft tissue and skeletal detail while avoiding the exposure to ionizing radiation inherent to computed tomography and nuclear medicine imaging techniques. This article reviews the more common current whole-body MRI techniques in children and the primary pathologies for which this imaging modality may be most useful to the radiologists and referring clinicians. J. MAGN. RESON. IMAGING 2016;44:783-793.

  1. A Framework for Analysis of Computational Imaging Systems: Role of Signal Prior, Sensor Noise and Multiplexing.

    PubMed

    Mitra, Kaushik; Cossairt, Oliver S; Veeraraghavan, Ashok

    2014-10-01

    Over the last decade, a number of computational imaging (CI) systems have been proposed for tasks such as motion deblurring, defocus deblurring and multispectral imaging. These techniques increase the amount of light reaching the sensor via multiplexing and then undo the deleterious effects of multiplexing by appropriate reconstruction algorithms. Given the widespread appeal and the considerable enthusiasm generated by these techniques, a detailed performance analysis of the benefits conferred by this approach is important. Unfortunately, a detailed analysis of CI has proven to be a challenging problem because performance depends equally on three components: (1) the optical multiplexing, (2) the noise characteristics of the sensor, and (3) the reconstruction algorithm which typically uses signal priors. A few recent papers [12], [30], [49] have performed analysis taking multiplexing and noise characteristics into account. However, analysis of CI systems under state-of-the-art reconstruction algorithms, most of which exploit signal prior models, has proven to be unwieldy. In this paper, we present a comprehensive analysis framework incorporating all three components. In order to perform this analysis, we model the signal priors using a Gaussian Mixture Model (GMM). A GMM prior confers two unique characteristics. First, GMM satisfies the universal approximation property which says that any prior density function can be approximated to any fidelity using a GMM with appropriate number of mixtures. Second, a GMM prior lends itself to analytical tractability allowing us to derive simple expressions for the `minimum mean square error' (MMSE) which we use as a metric to characterize the performance of CI systems. We use our framework to analyze several previously proposed CI techniques (focal sweep, flutter shutter, parabolic exposure, etc.), giving conclusive answer to the question: `How much performance gain is due to use of a signal prior and how much is due to

  2. Incorporation of prior knowledge for region of change imaging from sparse scan data in image-guided surgery

    NASA Astrophysics Data System (ADS)

    Lee, J.; Stayman, J. W.; Otake, Y.; Schafer, S.; Zbijewski, W.; Khanna, A. J.; Prince, J. L.; Siewerdsen, J. H.

    2012-02-01

    This paper proposes to utilize a patient-specific prior to augment intraoperative sparse-scan data to accurately reconstruct the aspects of the region that have changed by a surgical procedure in image-guided surgeries. When anatomical changes are introduced by a surgical procedure, only a sparse set of x-ray images are acquired, and the prior volume is registered to these data. Since all the information of the patient anatomy except for the surgical change is already known from the prior volume, we highlight only the change by creating difference images between the new scan and digitally reconstructed radiographs (DRR) computed from the registered prior volume. The region of change (RoC) is reconstructed from these sparse difference images by a penalized likelihood (PL) reconstruction method regularized by a compressed sensing penalty. When the surgical changes are local and relatively small, the RoC reconstruction involves only a small volume size and a small number of projections, allowing much faster computation and lower radiation dose than is needed to reconstruct the entire surgical volume. The reconstructed RoC merges with the prior volume to visualize an updated surgical field. We apply this novel approach to sacroplasty phantom data obtained from a conebeam CT (CBCT) test bench and vertebroplasty data with a fresh cadaver acquired from a C-arm CBCT system with a flat-panel detector (FPD).

  3. 11C-Acetate PET/CT Imaging in Localized Prostate Cancer: A study with MRI and Histopathologic Correlation

    PubMed Central

    Mena, Esther; Turkbey, Baris; Mani, Haresh; Adler, Stephen; Valera, Vladimir A.; Bernardo, Marcelino; Shah, Vijay; Pohida, Thomas; McKinney, Yolanda; Kwarteng, Gideon; Daar, Dagane; Lindenberg, Maria L.; Eclarinal, Philip; Wade, Revia; Linehan, W. Marston; Merino, Maria J.; Pinto, Peter A.; Choyke, Peter L.; Kurdziel, Karen A.

    2012-01-01

    This work characterizes the uptake of 11C-Acetate in prostate cancer (PCa), benign prostate hyperplasia (BPH) and normal prostate tissue in comparison with multi-parametric MRI, whole mount histopathology and clinical markers, to evaluate its potential utility for delineating intra-prostatic tumors in a population of patients with localized PCa. METHODS 39 men with presumed localized PCa underwent dynamic/static abdomen-pelvic 11C-Acetate PET/CT for 30-minutes and 3T multi-parametric (MP) MRI prior to prostatectomy. PET/CT images were registered to MRI using pelvic bones for initial rotation-translation, followed by manual adjustments to account for prostate motion and deformation from the MRI endorectal coil. Whole-mount pathology specimens were sectioned using an MRI-based patient specific mold resulting in improved registration between the MRI, PET and pathology. 11C-Acetate PET standardized uptake values were compared with MP-MRI and pathology. RESULTS 11C-Acetate uptake was rapid but reversible, peaking at 3–5 minutes post-injection and reaching a relative plateau at ~10 minutes. The average SUVmax(10–12min) of tumors was significantly higher than that of normal prostate tissue (4.4±2.05, range 1.8–9.2 vs. 2.1±0.94, range 0.7–3.4; p<0.001); however it was not significantly different from benign prostatic hyperplasia (4.8±2.01; range 1.8–8.8). A sector-based comparison with histopathology, including all tumors > 0.5 cm, revealed a sensitivity and specificity of 61.6 % and 80.0 % for 11C-Acetate PET/CT, and 82.3% and 95.1% for MRI, respectively. Considering only tumors >0.9 cm the 11C-Acetate accuracy was comparable to that of MRI. In a small cohort (n=9), 11C-Acetate uptake was independent of fatty acid synthase expression based on immunohistochemistry. CONCLUSION 11C-Acetate PET/CT demonstrates higher uptake in tumor foci than normal prostate tissue; however 11C-Acetate uptake in tumors is similar to BPH nodules. While 11C-Acetate PET/CT is not

  4. Spectral prior image constrained compressed sensing (spectral PICCS) for photon-counting computed tomography

    NASA Astrophysics Data System (ADS)

    Yu, Zhicong; Leng, Shuai; Li, Zhoubo; McCollough, Cynthia H.

    2016-09-01

    Photon-counting computed tomography (PCCT) is an emerging imaging technique that enables multi-energy imaging with only a single scan acquisition. To enable multi-energy imaging, the detected photons corresponding to the full x-ray spectrum are divided into several subgroups of bin data that correspond to narrower energy windows. Consequently, noise in each energy bin increases compared to the full-spectrum data. This work proposes an iterative reconstruction algorithm for noise suppression in the narrower energy bins used in PCCT imaging. The algorithm is based on the framework of prior image constrained compressed sensing (PICCS) and is called spectral PICCS; it uses the full-spectrum image reconstructed using conventional filtered back-projection as the prior image. The spectral PICCS algorithm is implemented using a constrained optimization scheme with adaptive iterative step sizes such that only two tuning parameters are required in most cases. The algorithm was first evaluated using computer simulations, and then validated by both physical phantoms and in vivo swine studies using a research PCCT system. Results from both computer-simulation and experimental studies showed substantial image noise reduction in narrow energy bins (43-73%) without sacrificing CT number accuracy or spatial resolution.

  5. Spectral prior image constrained compressed sensing (spectral PICCS) for photon-counting computed tomography

    NASA Astrophysics Data System (ADS)

    Yu, Zhicong; Leng, Shuai; Li, Zhoubo; McCollough, Cynthia H.

    2016-09-01

    Photon-counting computed tomography (PCCT) is an emerging imaging technique that enables multi-energy imaging with only a single scan acquisition. To enable multi-energy imaging, the detected photons corresponding to the full x-ray spectrum are divided into several subgroups of bin data that correspond to narrower energy windows. Consequently, noise in each energy bin increases compared to the full-spectrum data. This work proposes an iterative reconstruction algorithm for noise suppression in the narrower energy bins used in PCCT imaging. The algorithm is based on the framework of prior image constrained compressed sensing (PICCS) and is called spectral PICCS; it uses the full-spectrum image reconstructed using conventional filtered back-projection as the prior image. The spectral PICCS algorithm is implemented using a constrained optimization scheme with adaptive iterative step sizes such that only two tuning parameters are required in most cases. The algorithm was first evaluated using computer simulations, and then validated by both physical phantoms and in vivo swine studies using a research PCCT system. Results from both computer-simulation and experimental studies showed substantial image noise reduction in narrow energy bins (43–73%) without sacrificing CT number accuracy or spatial resolution.

  6. The Role of Imaging for Trigeminal Neuralgia: A Segmental Approach to High-Resolution MRI.

    PubMed

    Seeburg, Daniel P; Northcutt, Benjamin; Aygun, Nafi; Blitz, Ari M

    2016-07-01

    High-resolution MRI affords exquisite anatomic detail and allows radiologists to scrutinize the entire course of the trigeminal nerve (cranial nerve [CN] V). This article focuses first on the normal MRI appearance of the course of CN V and how best to image each segment. Special attention is then devoted to the role of MRI in presurgical evaluation of patients with neurovascular conflict and in identifying secondary causes of trigeminal neuralgia, including multiple sclerosis. Fundamental concepts in postsurgical imaging after neurovascular decompression are also addressed. Finally, how imaging has been used to better understand the etiology of trigeminal neuralgia is discussed. PMID:27324998

  7. Developing Training Image-Based Priors for Inversion of Subsurface Geophysical and Flow Data

    NASA Astrophysics Data System (ADS)

    Caers, J.

    2014-12-01

    Forecasting in subsurface formations, whether for groundwater, storage or oil & gas production, can rely on a wealth of geological information. Currently, most of this information remains underused in both the theory and practice of forecasting based on inverse models which heavily relies on spatial covariances and multi-Gaussian theory. By means of real field studies, I will provide an outline of how such geological information can be accounted through the construction and validation of a large set of training images and the generation of model realizations with MPS (multiple-point geostatistics). Often most critical in solving such inverse problems is the development of prior models that are later used for posterior sampling or stochastic search. I propose therefore a two-stage approach where the first stage consists of a validation of the training image-based prior with the geophysical and flow data. This stage will require only the generation of a few (100s) geological models and the forward modeling of the data response on these models. For geophysical data, the validation consists of comparing histograms of multi-scale wavelet transforms between the forward models and the field data. For flow data, the validation is based on a reduction of dimensionality of the forward response and the data using multi-dimensional scaling. The outcome of this validation is an estimate of the prior probability assigned to each training image, with several training images getting assigned zero probability (incompatible with field data). These prior probabilities are used in the second stage to actually invert for the data using stochastic search. In such stochastic search, I avoid parameterizing the model space and present methods that efficiently perform a direct search in the space of the validated training image-based prior model realizations.

  8. MR image super-resolution reconstruction using sparse representation, nonlocal similarity and sparse derivative prior.

    PubMed

    Zhang, Di; He, Jiazhong; Zhao, Yun; Du, Minghui

    2015-03-01

    In magnetic resonance (MR) imaging, image spatial resolution is determined by various instrumental limitations and physical considerations. This paper presents a new algorithm for producing a high-resolution version of a low-resolution MR image. The proposed method consists of two consecutive steps: (1) reconstructs a high-resolution MR image from a given low-resolution observation via solving a joint sparse representation and nonlocal similarity L1-norm minimization problem; and (2) applies a sparse derivative prior based post-processing to suppress blurring effects. Extensive experiments on simulated brain MR images and two real clinical MR image datasets validate that the proposed method achieves much better results than many state-of-the-art algorithms in terms of both quantitative measures and visual perception.

  9. Feasibility of Imaging Tissue Electrical Conductivity by Switching Field Gradients with MRI

    PubMed Central

    Gibbs, Eric; Liu, Chunlei

    2016-01-01

    Tissue conductivity is a biophysical marker of tissue structure and physiology. Present methods of measuring tissue conductivity are limited. Electrical impedance tomography, and magnetic resonance electrical impedance tomography rely on passing external current through the object being imaged, which prevents its use in most human imaging. Recently, the RF field used for MR excitation has been used to non-invasively measure tissue conductivity. This technique is promising, but conductivity at higher frequencies is less sensitive to tissue structure. Measuring tissue conductivity non-invasively at low frequencies remains elusive. It has been proposed that eddy currents generated during the rise and decay of gradient pulses could act as a current source to map low-frequency conductivity. This work centers on a gradient echo pulse sequence that uses large gradients prior to excitation to create eddy currents. The electric and magnetic fields during a gradient pulse are simulated by a finite-difference time-domain simulation. The sequence is also tested with a phantom and an animal MRI scanner equipped with gradients of high gradient strengths and slew rate. The simulation demonstrates that eddy currents in materials with conductivity similar to biological tissue decay with a half-life on the order of nanoseconds and any eddy currents generated prior to excitation decay completely before influencing the RF signal. Gradient-induced eddy currents can influence phase accumulation after excitation but the effect is too small to image. The animal scanner images show no measurable phase accumulation. Measuring low-frequency conductivity by gradient-induced eddy currents is presently unfeasible. PMID:26844302

  10. Hyperpolarized 129Xe MRI: A Viable Functional Lung Imaging Modality?

    PubMed Central

    Patz, Samuel; Hersman, F. William; Muradian, Iga; Hrovat, Mirko I.; Ruset, Iulian C.; Ketel, Stephen; Jacobson, Francine; Topulos, George P.; Hatabu, Hiroto; Butler, James P.

    2008-01-01

    The majority of researchers investigating hyperpolarized gas MRI as a candidate functional lung imaging modality have used 3He as their imaging agent of choice rather than 129Xe. This preference has been predominantly due to, 3He providing stronger signals due to higher levels of polarization and higher gyromagnetic ratio, as well as its being easily available to more researchers due to availability of polarizers (USA) or ease of gas transport (Europe). Most researchers agree, however, that hyperpolarized 129Xe will ultimately emerge as the imaging agent of choice due to its unlimited supply in nature and its falling cost. Our recent polarizer technology delivers vast improvements in hyperpolarized 129Xe output. Using this polarizer, we have demonstrated the unique property of xenon to measure alveolar surface area noninvasively. In this article, we describe our human protocols and their safety, and our results for the measurement of the partial pressure of pulmonary oxygen (pO2) by observation of 129Xe signal decay. We note that the measurement of pO2 by observation of 129Xe signal decay is more complex than that for 3He because of an additional signal loss mechanism due to interphase diffusion of 129Xe from alveolar gas spaces to septal tissue. This results in measurements of an equivalent pO2 that accounts for both traditional T1 decay from pO2 and that from interphase diffusion. We also provide an update on new technological advancements that form the foundation for an improved compact design polarizer as well as improvements that provide another order-of-magnitude scale-up in xenon polarizer output. PMID:17890035

  11. Recent Advances in the Imaging Diagnosis of Hepatocellular Carcinoma: Value of Gadoxetic Acid-Enhanced MRI

    PubMed Central

    Joo, Ijin; Lee, Jeong Min

    2016-01-01

    Magnetic resonance imaging (MRI) using gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DPTA), or gadoxetic acid for short, is a hepatocyte-specific contrast agent which is now increasingly used for the detection and characterization of focal hepatic lesions, particularly in patients at high-risk of developing hepatocellular carcinomas (HCC). In fact, several recent guidelines now recognize gadoxetic acid-enhanced MRI (Gd-EOB-MRI) as the primary diagnostic imaging modality for the noninvasive diagnosis of HCC, although it must be noted that several major guidelines still include only extracellular contrast media-enhanced computed tomography and MRI. The primary merits of Gd-EOB-MRI lie in the fact that it can provide not only dynamic imaging, but also hepatobiliary phase (HBP) imaging which can lead to high lesion-to-liver contrast and give additional information regarding hepatocyte uptake via organic anion transporting polypeptides. This, in turn, allows higher sensitivity in detecting small HCCs and helps provide additional information regarding the multistep process of hepatocarcinogenesis. Indeed, many recent studies have investigated the diagnostic value of Gd-EOB-MRI for early HCCs as well as its role as a potential imaging biomarker in predicting outcome. We herein review the recent advances in the imaging diagnosis of HCCs focusing on the applications of Gd-EOB-MRI and the challenging issues that remain. PMID:26989660

  12. Recent Advances in the Imaging Diagnosis of Hepatocellular Carcinoma: Value of Gadoxetic Acid-Enhanced MRI.

    PubMed

    Joo, Ijin; Lee, Jeong Min

    2016-02-01

    Magnetic resonance imaging (MRI) using gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DPTA), or gadoxetic acid for short, is a hepatocyte-specific contrast agent which is now increasingly used for the detection and characterization of focal hepatic lesions, particularly in patients at high-risk of developing hepatocellular carcinomas (HCC). In fact, several recent guidelines now recognize gadoxetic acid-enhanced MRI (Gd-EOB-MRI) as the primary diagnostic imaging modality for the noninvasive diagnosis of HCC, although it must be noted that several major guidelines still include only extracellular contrast media-enhanced computed tomography and MRI. The primary merits of Gd-EOB-MRI lie in the fact that it can provide not only dynamic imaging, but also hepatobiliary phase (HBP) imaging which can lead to high lesion-to-liver contrast and give additional information regarding hepatocyte uptake via organic anion transporting polypeptides. This, in turn, allows higher sensitivity in detecting small HCCs and helps provide additional information regarding the multistep process of hepatocarcinogenesis. Indeed, many recent studies have investigated the diagnostic value of Gd-EOB-MRI for early HCCs as well as its role as a potential imaging biomarker in predicting outcome. We herein review the recent advances in the imaging diagnosis of HCCs focusing on the applications of Gd-EOB-MRI and the challenging issues that remain. PMID:26989660

  13. Correction of projective distortion in long-image-sequence mosaics without prior information

    NASA Astrophysics Data System (ADS)

    Yang, Chenhui; Mao, Hongwei; Abousleman, Glen; Si, Jennie

    2010-04-01

    Image mosaicking is the process of piecing together multiple video frames or still images from a moving camera to form a wide-area or panoramic view of the scene being imaged. Mosaics have widespread applications in many areas such as security surveillance, remote sensing, geographical exploration, agricultural field surveillance, virtual reality, digital video, and medical image analysis, among others. When mosaicking a large number of still images or video frames, the quality of the resulting mosaic is compromised by projective distortion. That is, during the mosaicking process, the image frames that are transformed and pasted to the mosaic become significantly scaled down and appear out of proportion with respect to the mosaic. As more frames continue to be transformed, important target information in the frames can be lost since the transformed frames become too small, which eventually leads to the inability to continue further. Some projective distortion correction techniques make use of prior information such as GPS information embedded within the image, or camera internal and external parameters. Alternatively, this paper proposes a new algorithm to reduce the projective distortion without using any prior information whatsoever. Based on the analysis of the projective distortion, we approximate the projective matrix that describes the transformation between image frames using an affine model. Using singular value decomposition, we can deduce the affine model scaling factor that is usually very close to 1. By resetting the image scale of the affine model to 1, the transformed image size remains unchanged. Even though the proposed correction introduces some error in the image matching, this error is typically acceptable and more importantly, the final mosaic preserves the original image size after transformation. We demonstrate the effectiveness of this new correction algorithm on two real-world unmanned air vehicle (UAV) sequences. The proposed method is

  14. Echo Planar Imaging before and after fMRI: A personal history

    PubMed Central

    Cohen, Mark S.; Schmitt, Franz

    2012-01-01

    Echo-planar imaging (EPI) plays a crucial role in functional MRI. Focusing especially on the period from 1988 to 1992, the authors offer personal recollections, on the development of practical means of deploying EPI, the people that participated, and its impact on MRI in general. PMID:22266173

  15. Anatomy-guided brain PET imaging incorporating a joint prior model

    NASA Astrophysics Data System (ADS)

    Lu, Lijun; Ma, Jianhua; Feng, Qianjin; Chen, Wufan; Rahmim, Arman

    2015-03-01

    We proposed a maximum a posterior (MAP) framework for incorporating information from co-registered anatomical images into PET image reconstruction through a novel anato-functional joint prior. The characteristic of the utilized hyperbolic potential function is determinate by the voxel intensity differences within the anatomical image, while the penalization is computed based on voxel intensity differences in reconstructed PET images. Using realistic simulated 18FDG PET scan data, we optimized the performance of the proposed MAP reconstruction with the joint prior (JP-MAP) and compared its performance with conventional 3D MLEM and 3D MAP reconstructions. The proposed JP-MAP reconstruction algorithm resulted in quantitatively enhanced reconstructed images, as demonstrated in extensive FDG PET simulation study. The proposed method was also tested on a 20 min Florbetapir patient study performed on the high-resolution research tomograph. It was shown to outperform conventional methods in visual as well as quantitative accuracy assessment (in terms of regional noise versus activity value performance). The JP-MAP method was also compared with another MR-guided MAP reconstruction method, utilizing the Bowsher prior and was seen to result in some quantitative enhancements, especially in the case of MR-PET mis-registrations, and a definitive improvement in computational performance.

  16. The use of geometric prior information in Bayesian tomographic image reconstruction: A preliminary report

    SciTech Connect

    Lacer, J.; ter Haar Romeny, B.M.; Viergever, M.A.

    1992-06-01

    In this paper we examine the possibility of using pure geometrical information from a prior image to assist in the reconstruction of tomographic data sets with lower number of counts. The situation can arise in dynamic studies, for example, in which the sum image from a number of time frames is available, defining desired regions-of-interest (ROI`s) with good accuracy, and the time evolution of uptake in those ROI`s needs to be obtained from the low count individual data sets. `the prior information must be purely geometrical in such a case, so that the activity in the ROI`s of the prior does not influence the estimated uptake from the individual time frames. It is also desired that the prior does not impose any other conditions on the reconstructions, i.e., no smoothness or deviation from a known set of values is desired. We attack this problem in the framework of Vision Response Functions (VRFs), based on the work done by J.J. Koenderink in Utrecht. We show that there are assemblies of VRF`s that can be presented in a form that is invariant with respect to rotations and translations and that some functions of those invariants can convey the desired geometric prior information independent of the level of activity in the ROI`S, except at very low levels.

  17. Multimodal in vivo MRI and NIRF imaging of bladder tumor using peptide conjugated glycol chitosan nanoparticles

    NASA Astrophysics Data System (ADS)

    Key, Jaehong; Dhawan, Deepika; Knapp, Deborah W.; Kim, Kwangmeyung; Kwon, Ick Chan; Choi, Kuiwon; Leary, James F.

    2012-03-01

    Exact detection and complete removal of cancer is a key point to minimize cancer recurrence. However, it is currently very difficult to detect small tumors inside human body and continuously monitor tumors using a non-invasive imaging modality. Presently, positron emission tomography (PET) can provide the most sensitive cancer images in the human body. However, PET imaging has very limited imaging time because they typically use isotopes with short halflives. PET imaging cannot also visualize anatomical information. Magnetic resonance imaging (MRI) can provide highresolution images inside the body but it has a low sensitivity, so MRI contrast agents are necessary to enhance the contrast of tumor. Near infrared fluorescent (NIRF) imaging has a good sensitivity to visualize tumor using optical probes, but it has a very limited tissue penetration depth. Therefore, we developed multi-modality nanoparticles for MRI based diagnosis and NIRF imaging based surgery of cancer. We utilized glycol chitosan of 350 nm as a vehicle for MRI contrast agents and NIRF probes. The glycol chitosan nanoparticles were conjugated with NIRF dye, Cy5.5 and bladder cancer targeting peptides to increase the internalization of cancer. For MR contrast effects, iron oxide based 22 nm nanocubes were physically loaded into the glycol chitosan nanoparticles. The nanoparticles were characterized and evaluated in bladder tumor bearing mice. Our study suggests the potential of our nanoparticles by both MRI and NIRF imaging for tumor diagnosis and real-time NIRF image-guided tumor surgery.

  18. Medical image segmentation using minimal path deformable models with implicit shape priors.

    PubMed

    Yan, Pingkun; Kassim, Ashraf A

    2006-10-01

    This paper presents a new method for segmentation of medical images by extracting organ contours, using minimal path deformable models incorporated with statistical shape priors. In our approach, boundaries of structures are considered as minimal paths, i.e., paths associated with the minimal energy, on weighted graphs. Starting from the theory of minimal path deformable models, an intelligent "worm" algorithm is proposed for segmentation, which is used to evaluate the paths and finally find the minimal path. Prior shape knowledge is incorporated into the segmentation process to achieve more robust segmentation. The shape priors are implicitly represented and the estimated shapes of the structures can be conveniently obtained. The worm evolves under the joint influence of the image features, its internal energy, and the shape priors. The contour of the structure is then extracted as the worm trail. The proposed segmentation framework overcomes the short-comings of existing deformable models and has been successfully applied to segmenting various medical images. PMID:17044401

  19. The hidden-Markov brain: comparison and inference of white matter hyperintensities on magnetic resonance imaging (MRI)

    NASA Astrophysics Data System (ADS)

    Pham, Tuan D.; Salvetti, Federica; Wang, Bing; Diani, Marco; Heindel, Walter; Knecht, Stefan; Wersching, Heike; Baune, Bernhard T.; Berger, Klaus

    2011-02-01

    Rating and quantification of cerebral white matter hyperintensities on magnetic resonance imaging (MRI) are important tasks in various clinical and scientific settings. As manual evaluation is time consuming and imprecise, much effort has been made to automate the quantification of white matter hyperintensities. There is rarely any report that attempts to study the similarity/dissimilarity of white matter hyperintensity patterns that have different sizes, shapes and spatial localizations on the MRI. This paper proposes an original computational neuroscience framework for such a conceptual study with a standpoint that the prior knowledge about white matter hyperintensities can be accumulated and utilized to enable a reliable inference of the rating of a new white matter hyperintensity observation. This computational approach for rating inference of white matter hyperintensities, which appears to be the first study, can be utilized as a computerized rating-assisting tool and can be very economical for diagnostic evaluation of brain tissue lesions.

  20. A new combined prior based reconstruction method for compressed sensing in 3D ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Uddin, Muhammad S.; Islam, Rafiqul; Tahtali, Murat; Lambert, Andrew J.; Pickering, Mark R.

    2015-03-01

    Ultrasound (US) imaging is one of the most popular medical imaging modalities, with 3D US imaging gaining popularity recently due to its considerable advantages over 2D US imaging. However, as it is limited by long acquisition times and the huge amount of data processing it requires, methods for reducing these factors have attracted considerable research interest. Compressed sensing (CS) is one of the best candidates for accelerating the acquisition rate and reducing the data processing time without degrading image quality. However, CS is prone to introduce noise-like artefacts due to random under-sampling. To address this issue, we propose a combined prior-based reconstruction method for 3D US imaging. A Laplacian mixture model (LMM) constraint in the wavelet domain is combined with a total variation (TV) constraint to create a new regularization regularization prior. An experimental evaluation conducted to validate our method using synthetic 3D US images shows that it performs better than other approaches in terms of both qualitative and quantitative measures.

  1. Delineating potential epileptogenic areas utilizing resting functional magnetic resonance imaging (fMRI) in epilepsy patients.

    PubMed

    Pizarro, Ricardo; Nair, Veena; Meier, Timothy; Holdsworth, Ryan; Tunnell, Evelyn; Rutecki, Paul; Sillay, Karl; Meyerand, Mary E; Prabhakaran, Vivek

    2016-08-01

    Seizure localization includes neuroimaging like electroencephalogram, and magnetic resonance imaging (MRI) with limited ability to characterize the epileptogenic network. Temporal clustering analysis (TCA) characterizes epileptogenic network congruent with interictal epileptiform discharges by clustering together voxels with transient signals. We generated epileptogenic areas for 12 of 13 epilepsy patients with TCA, congruent with different areas of seizure onset. Resting functional MRI (fMRI) scans are noninvasive, and can be acquired quickly, in patients with different levels of severity and function. Analyzing resting fMRI data using TCA is quick and can complement clinical methods to characterize the epileptogenic network. PMID:27362339

  2. Characterization of statistical prior image constrained compressed sensing (PICCS): II. Application to dose reduction

    PubMed Central

    Lauzier, Pascal Thériault; Chen, Guang-Hong

    2013-01-01

    Purpose: The ionizing radiation imparted to patients during computed tomography exams is raising concerns. This paper studies the performance of a scheme called dose reduction using prior image constrained compressed sensing (DR-PICCS). The purpose of this study is to characterize the effects of a statistical model of x-ray detection in the DR-PICCS framework and its impact on spatial resolution. Methods: Both numerical simulations with known ground truth and in vivo animal dataset were used in this study. In numerical simulations, a phantom was simulated with Poisson noise and with varying levels of eccentricity. Both the conventional filtered backprojection (FBP) and the PICCS algorithms were used to reconstruct images. In PICCS reconstructions, the prior image was generated using two different denoising methods: a simple Gaussian blur and a more advanced diffusion filter. Due to the lack of shift-invariance in nonlinear image reconstruction such as the one studied in this paper, the concept of local spatial resolution was used to study the sharpness of a reconstructed image. Specifically, a directional metric of image sharpness, the so-called pseudopoint spread function (pseudo-PSF), was employed to investigate local spatial resolution. Results: In the numerical studies, the pseudo-PSF was reduced from twice the voxel width in the prior image down to less than 1.1 times the voxel width in DR-PICCS reconstructions when the statistical model was not included. At the same noise level, when statistical weighting was used, the pseudo-PSF width in DR-PICCS reconstructed images varied between 1.5 and 0.75 times the voxel width depending on the direction along which it was measured. However, this anisotropy was largely eliminated when the prior image was generated using diffusion filtering; the pseudo-PSF width was reduced to below one voxel width in that case. In the in vivo study, a fourfold improvement in CNR was achieved while qualitatively maintaining sharpness

  3. Tag removal in cardiac tagged MRI images using coupled dictionary learning.

    PubMed

    Makram, Abram W; Rushdi, Muhammad A; Khalifa, Ayman M; El-Wakad, Mohamed T

    2015-01-01

    Tagged Magnetic Resonance Imaging (tMRI) is considered to be the gold standard for quantitative assessment of the cardiac local functions. However, the tagging patterns and low myocardium-to-blood-pool contrast of tagged images bring great challenges to cardiac image processing and analysis tasks such as myocardium segmentation and tracking. Hence, there has been growing interest in techniques for removing tagging lines. In this work, a method for removing tagging patterns in tagged MR images using a coupled dictionary learning (CDL) model is proposed. In this model, identical sparse representations are assumed for image patches in the tagged MRI and corresponding cine MRI image spaces. First, we learn a dictionary for the tagged MRI image space. Then, we compute a dictionary for the cine MRI image space so that corresponding tagged and cine patches have the same sparse codes in terms of their respective dictionaries. Finally, in order to produce the de-tagged (cine version) of a test tagged image, the sparse codes of the tagged patches and the trained cine dictionary are used together to construct the de-tagged patches. We have tested this tag removal method on a dataset of tagged cardiac MR images. Our experimental results compared favorably with a recently proposed tag removal method that removes tags in the frequency domain using an optimal band-stop filter of harmonic peaks.

  4. [Wilm's tumor. Diagnostic capacities of magnetic resonance imaging. MRI-pathomorphological comparison].

    PubMed

    Dombrovskii, V

    2001-01-01

    The accuracy of magnetic resonance imaging (MRI) in the diagnosis of Wilms' tumor (WT) and in the evaluation of preoperative chemotherapy (PCH) efficiency was investigated and compared with histopathological data of 56 children and infants with proven retroperitoneum neoplasma (WT--49, neuroblastoma--6, congenital mesoblastic nephroma--1). The author described the WT MRI-semiotics in general and in particular for its changes during the preoperative chemotherapy. The formula for calculation of tumor reduction index is suggested. The MRI sensitivity (100%), specificity (77.8%) and accuracy (91.1%) are detected. The high positive correlation level between the MRI and pathologic findings, concerning WT dimensions, pseudocapsule presence and safety, tumor structure secondary alterations and tumor spreading was found. At the same time, the specific MRI criteria for the different histological types of WT were not found. MRI is confirmed to be an accurate tool for diagnostic monitoring of patients with WT and other retroperitoneum neoplasms.

  5. A probability tracking approach to segmentation of ultrasound prostate images using weak shape priors

    NASA Astrophysics Data System (ADS)

    Xu, Robert S.; Michailovich, Oleg V.; Solovey, Igor; Salama, Magdy M. A.

    2010-03-01

    Prostate specific antigen density is an established parameter for indicating the likelihood of prostate cancer. To this end, the size and volume of the gland have become pivotal quantities used by clinicians during the standard cancer screening process. As an alternative to manual palpation, an increasing number of volume estimation methods are based on the imagery data of the prostate. The necessity to process large volumes of such data requires automatic segmentation algorithms, which can accurately and reliably identify the true prostate region. In particular, transrectal ultrasound (TRUS) imaging has become a standard means of assessing the prostate due to its safe nature and high benefit-to-cost ratio. Unfortunately, modern TRUS images are still plagued by many ultrasound imaging artifacts such as speckle noise and shadowing, which results in relatively low contrast and reduced SNR of the acquired images. Consequently, many modern segmentation methods incorporate prior knowledge about the prostate geometry to enhance traditional segmentation techniques. In this paper, a novel approach to the problem of TRUS segmentation, particularly the definition of the prostate shape prior, is presented. The proposed approach is based on the concept of distribution tracking, which provides a unified framework for tracking both photometric and morphological features of the prostate. In particular, the tracking of morphological features defines a novel type of "weak" shape priors. The latter acts as a regularization force, which minimally bias the segmentation procedure, while rendering the final estimate stable and robust. The value of the proposed methodology is demonstrated in a series of experiments.

  6. Dose reduction using prior image constrained compressed sensing (DR-PICCS)

    NASA Astrophysics Data System (ADS)

    Tang, Jie; Thériault Lauzier, Pascal; Chen, Guang-Hong

    2011-03-01

    A technique for dose reduction using prior image constrained compressed sensing (DR-PICCS) in computed tomography (CT) is proposed in this work. In DR-PICCS, a standard FBP reconstructed image is forward projected to get a fully sampled projection data set. Meanwhile, it is low-pass filtered and used as the prior image in the PICCS reconstruction framework. Next, the prior image and the forward projection data are used together by the PICCS algorithm to obtain a low noise DR-PICCS reconstruction, which maintains the spatial resolution of the original FBP images. The spatial resolution of DR-PICCS was studied using a Catphan phantom by MTF measurement. The noise reduction factor, CT number change and noise texture were studied using human subject data consisting of 20 CT colonography exams performed under an IRB-approved protocol. In each human subject study, six ROIs (two soft tissue, two colonic air columns, and two subcutaneous fat) were selected for the CT number and noise measurements study. Skewness and kurtosis were used as figures of merit to indicate the noise texture. A Bland-Altman analysis was performed to study the accuracy of the CT number. The results showed that, compared with FBP reconstructions, the MTF curve shows very little change in DR-PICCS reconstructions, spatial resolution loss is less than 0.1 lp/cm, and the noise standard deviation can be reduced by a factor of 3 with DR-PICCS. The CT numbers in FBP and DR-PICCS reconstructions agree well, which indicates that DR-PICCS does not change CT numbers. The noise textures indicators measured from DR-PICCS images are in a similar range as FBP images.

  7. Algorithms for biomagnetic source imaging with prior anatomical and physiological information

    SciTech Connect

    Hughett, P W

    1995-12-01

    This dissertation derives a new method for estimating current source amplitudes in the brain and heart from external magnetic field measurements and prior knowledge about the probable source positions and amplitudes. The minimum mean square error estimator for the linear inverse problem with statistical prior information was derived and is called the optimal constrained linear inverse method (OCLIM). OCLIM includes as special cases the Shim-Cho weighted pseudoinverse and Wiener estimators but allows more general priors and thus reduces the reconstruction error. Efficient algorithms were developed to compute the OCLIM estimate for instantaneous or time series data. The method was tested in a simulated neuromagnetic imaging problem with five simultaneously active sources on a grid of 387 possible source locations; all five sources were resolved, even though the true sources were not exactly at the modeled source positions and the true source statistics differed from the assumed statistics.

  8. Structural Image Analysis of the Brain in Neuropsychology Using Magnetic Resonance Imaging (MRI) Techniques.

    PubMed

    Bigler, Erin D

    2015-09-01

    Magnetic resonance imaging (MRI) of the brain provides exceptional image quality for visualization and neuroanatomical classification of brain structure. A variety of image analysis techniques provide both qualitative as well as quantitative methods to relate brain structure with neuropsychological outcome and are reviewed herein. Of particular importance are more automated methods that permit analysis of a broad spectrum of anatomical measures including volume, thickness and shape. The challenge for neuropsychology is which metric to use, for which disorder and the timing of when image analysis methods are applied to assess brain structure and pathology. A basic overview is provided as to the anatomical and pathoanatomical relations of different MRI sequences in assessing normal and abnormal findings. Some interpretive guidelines are offered including factors related to similarity and symmetry of typical brain development along with size-normalcy features of brain anatomy related to function. The review concludes with a detailed example of various quantitative techniques applied to analyzing brain structure for neuropsychological outcome studies in traumatic brain injury.

  9. Prior CT imaging history for patients who undergo PAN CT for acute traumatic injury

    PubMed Central

    Kenter, Jeremy; Blow, Osbert; Krall, Scott P.; Gest, Albert; Smith, Cynthia

    2015-01-01

    Objective. A single PAN scan may provide more radiation to a patient than is felt to be safe within a one-year period. Our objective was to determine how many patients admitted to the trauma service following a PAN scan had prior CT imaging within our six-hospital system. Methods. We performed a secondary analysis of a prospectively collected trauma registry. The study was based at a level-two trauma center and five affiliated hospitals, which comprise 70.6% of all Emergency Department visits within a twelve county region of southern Texas. Electronic medical records were reviewed dating from the point of trauma evaluation back to December 5, 2005 to determine evidence of prior CT imaging. Results. There were 867 patients were admitted to the trauma service between January 1, 2012 and December 31, 2012. 460 (53%) received a PAN scan and were included in the study group. The mean age of the study group was 37.7 ± 1.54 years old, 24.8% were female, and the mean ISS score was 13.4 ± 1.07. The most common mechanism of injury was motor vehicle collision (47%). 65 (14%; 95% CI [11–18]%) of the patients had at least one prior CT. The most common prior studies performed were: CT head (29%; 19–42%), CT Face (29%; 19–42%) and CT Abdomen and Pelvis (18%; 11–30%). Conclusion. Within our trauma registry, 14% of patients had prior CT imaging within our hospital system before their traumatic event and PAN scan. PMID:26056616

  10. [The Diagnostic Value of Pre-Biopsy Magnetic Resonance Imaging (MRI) for Detecting Prostate Cancer].

    PubMed

    Mori, Kohei; Miyoshi, Yasuhide; Yoneyama, Shuko; Ishida, Hiroaki; Hattori, Yusuke; Teranishi, Jun-ichi; Kondo, Keiichi; Noguchi, Kazumi

    2016-01-01

    We examined the value of pre-biopsy magnetic resonance imaging (MRI) for detecting prostate cancer. We analyzed 267 men with prostate-specific antigen (PSA) levels of 3-10 ng/ml who underwent systematic prostate needle biopsy. From April 2009 to March 2011, a total of 98 male patients underwent 16-core prostatic biopsies without pre-biopsy magnetic resonance imaging (MRI) (nonenforcement group). From April 2011 to March 2013, 169 men underwent pre-biopsy MRI [T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI)] (enforcement group). When MRI findings indicated cancer in the latter group, in addition to the systematic 16-core biopsy one or two targeted biopsies were performed. Patients without suspicious MRI findings underwent only systematic 16-core biopsy. Cancer detection rates in the nonenforcement and enforcement groups were 42.9% (48/92) and 46. 2% (78/169), respectively. The difference did not reach significance (p=0.612). Although the cancer detection rates were 39.4% (41/104) in the MRI-negative group and 56. 9% (37/65) in the MRI-positive group (p=0.039), the sensitivity and specificity for cancer detection by MRI were relatively low: 47.4% and 69.2%, respectively. By receiver-operating curve analysis, the area under the curve for cancer detection by MRI was only 0.583. There were two study limitations. First, the patient sample size was small. Second, it is unclear whether an adequate sample of the suspicious lesion was obtained by biopsy. We thus demonstrated that it might be improper to base a diagnosis solely on pre-biopsy MRI (T2WI and DWI) findings in men with serum PSA levels of 3-10 ng/ml.

  11. Bayesian blind separation and deconvolution of dynamic image sequences using sparsity priors.

    PubMed

    Tichy, Ondrej; Smidl, Vaclav

    2015-01-01

    A common problem of imaging 3-D objects into image plane is superposition of the projected structures. In dynamic imaging, projection overlaps of organs and tissues complicate extraction of signals specific to individual structures with different dynamics. The problem manifests itself also in dynamic tomography as tissue mixtures are present in voxels. Separation of signals specific to dynamic structures belongs to the category of blind source separation. It is an underdetermined problem with many possible solutions. Existing separation methods select the solution that best matches their additional assumptions on the source model. We propose a novel blind source separation method based on probabilistic model of dynamic image sequences assuming each source dynamics as convolution of an input function and a source specific kernel (modeling organ impulse response or retention function). These assumptions are formalized as a Bayesian model with hierarchical prior and solved by the Variational Bayes method. The proposed prior distribution assigns higher probability to sparse source images and sparse convolution kernels. We show that the results of separation are relevant to selected tasks of dynamic renal scintigraphy. Accuracy of tissue separation with simulated and clinical data provided by the proposed method outperformed accuracy of previously developed methods measured by the mean square and mean absolute errors of estimation of simulated sources and the sources separated by an expert physician. MATLAB implementation of the algorithm is available for download. PMID:25181364

  12. Computer-assisted scheme for automated determination of imaging planes in cervical spinal cord MRI

    NASA Astrophysics Data System (ADS)

    Tsurumaki, Masaki; Tsai, Du-Yih; Lee, Yongbum; Sekiya, Masaru; Kazama, Kiyoko

    2009-02-01

    This paper presents a computerized scheme to assist MRI operators in accurate and rapid determination of sagittal sections for MRI exam of cervical spinal cord. The algorithm of the proposed scheme consisted of 6 steps: (1) extraction of a cervical vertebra containing spinal cord from an axial localizer image; (2) extraction of spinal cord with sagittal image from the extracted vertebra; (3) selection of a series of coronal localizer images corresponding to various, involved portions of the extracted spinal cord with sagittal image; (4) generation of a composite coronal-plane image from the obtained coronal images; (5) extraction of spinal cord from the obtained composite image; (6) determination of oblique sagittal sections from the detected location and gradient of the extracted spinal cord. Cervical spine images obtained from 25 healthy volunteers were used for the study. A perceptual evaluation was performed by five experienced MRI operators. Good agreement between the automated and manual determinations was achieved. By use of the proposed scheme, average execution time was reduced from 39 seconds/case to 1 second/case. The results demonstrate that the proposed scheme can assist MRI operators in performing cervical spinal cord MRI exam accurately and rapidly.

  13. The utility of high-resolution intraoperative MRI in endoscopic transsphenoidal surgery for pituitary macroadenomas: early experience in the Advanced Multimodality Image Guided Operating suite

    PubMed Central

    Zaidi, Hasan A.; De Los Reyes, Kenneth; Barkhoudarian, Garni; Litvack, Zachary N.; Bi, Wenya Linda; Rincon-Torroella, Jordina; Mukundan, Srinivasan; Dunn, Ian F.; Laws, Edward R.

    2016-01-01

    Objective Endoscopic skull base surgery has become increasingly popular among the skull base surgery community, with improved illumination and angled visualization potentially improving tumor resection rates. Intraoperative MRI (iMRI) is used to detect residual disease during the course of the resection. This study is an investigation of the utility of 3-T iMRI in combination with transnasal endoscopy with regard to gross-total resection (GTR) of pituitary macroadenomas. Methods The authors retrospectively reviewed all endoscopic transsphenoidal operations performed in the Advanced Multimodality Image Guided Operating (AMIGO) suite from November 2011 to December 2014. Inclusion criteria were patients harboring presumed pituitary macroadenomas with optic nerve or chiasmal compression and visual loss, operated on by a single surgeon. Results Of the 27 patients who underwent transsphenoidal resection in the AMIGO suite, 20 patients met the inclusion criteria. The endoscope alone, without the use of iMRI, would have correctly predicted 13 (65%) of 20 cases. Gross-total resection was achieved in 12 patients (60%) prior to MRI. Intraoperative MRI helped convert 1 STR and 4 NTRs to GTRs, increasing the number of GTRs from 12 (60%) to 16 (80%). Conclusions Despite advances in visualization provided by the endoscope, the incidence of residual disease can potentially place the patient at risk for additional surgery. The authors found that iMRI can be useful in detecting unexpected residual tumor. The cost-effectiveness of this tool is yet to be determined. PMID:26926058

  14. Image-domain shading correction for cone-beam CT without prior patient information.

    PubMed

    Fan, Qiyong; Lu, Bo; Park, Justin C; Niu, Tianye; Li, Jonathan G; Liu, Chihray; Zhu, Lei

    2015-01-01

    In the era of high-precision radiotherapy, cone-beam CT (CBCT) is frequently utilized for on-board treatment guidance. However, CBCT images usually contain severe shading artifacts due to strong photon scatter from illumination of a large volume and non-optimized patient-specific data measurements, limiting the full clinical applications of CBCT. Many algorithms have been proposed to alleviate this problem by data correction on projections. Sophisticated methods have also been designed when prior patient information is available. Nevertheless, a standard, efficient, and effective approach with large applicability remains elusive for current clinical practice. In this work, we develop a novel algorithm for shading correction directly on CBCT images. Distinct from other image-domain correction methods, our approach does not rely on prior patient information or prior assumption of patient data. In CBCT, projection errors (mostly from scatter and non-ideal usage of bowtie filter) result in dominant low-frequency shading artifacts in image domain. In circular scan geometry, these artifacts often show global or local radial patterns. Hence, the raw CBCT images are first preprocessed into the polar coordinate system. Median filtering and polynomial fitting are applied on the transformed image to estimate the low-frequency shading artifacts (referred to as the bias field) angle-by-angle and slice-by-slice. The low-pass filtering process is done firstly along the angular direction and then the radial direction to preserve image contrast. The estimated bias field is then converted back to the Cartesian coordinate system, followed by 3D low-pass filtering to eliminate possible high-frequency components. The shading-corrected image is finally obtained as the uncorrected volume divided by the bias field. The proposed algorithm was evaluated on CBCT images of a pelvis patient and a head patient. Mean CT number values and spatial non-uniformity on the reconstructed images were

  15. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging

    PubMed Central

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-01-01

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools—and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids’ apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  16. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging.

    PubMed

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-07-15

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools--and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids' apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  17. Reliability of Early Magnetic Resonance Imaging (MRI) and Necessity of Repeating MRI in Noncooled and Cooled Infants With Neonatal Encephalopathy.

    PubMed

    Chakkarapani, Elavazhagan; Poskitt, Kenneth J; Miller, Steven P; Zwicker, Jill G; Xu, Qi; Wong, Darren S T; Roland, Elke H; Hill, Alan; Chau, Vann

    2016-04-01

    In cooled newborns with encephalopathy, although late magnetic resonance imaging (MRI) scan (10-14 days of age) is reliable in predicting long-term outcome, it is unknown whether early scan (3-6 days of life) is. We compared the predominant pattern and extent of lesion between early and late MRI in 89 term neonates with neonatal encephalopathy. Forty-three neonates (48%) were cooled. The predominant pattern of lesions and the extent of lesion in the watershed region agreed near perfectly in noncooled (kappa = 0.94; k = 0.88) and cooled (k = 0.89; k = 0.87) infants respectively. There was perfect agreement in the extent of lesion in the basal nuclei in noncooled infants (k = 0.83) and excellent agreement in cooled infants (k = 0.67). Changes in extent of lesions on late MRI occurred in 19 of 89 infants, with higher risk in infants with hypoglycemia and moderate-severe lesions in basal nuclei. In most term neonates with neonatal encephalopathy, early MRI (relative to late scan) robustly predicts the predominant pattern and extent of injury.

  18. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging.

    PubMed

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-07-15

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools--and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids' apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas.

  19. Characterizing Response to Elemental Unit of Acoustic Imaging Noise: An fMRI Study

    PubMed Central

    Luh, Wen-Ming; Talavage, Thomas M.

    2010-01-01

    Acoustic imaging noise produced during functional magnetic resonance imaging (fMRI) studies can hinder auditory fMRI research analysis by altering the properties of the acquired time-series data. Acoustic imaging noise can be especially confounding when estimating the time course of the hemodynamic response (HDR) in auditory event-related fMRI (fMRI) experiments. This study is motivated by the desire to establish a baseline function that can serve not only as a comparison to other quantities of acoustic imaging noise for determining how detrimental is one's experimental noise, but also as a foundation for a model that compensates for the response to acoustic imaging noise. Therefore, the amplitude and spatial extent of the HDR to the elemental unit of acoustic imaging noise (i.e., a single ping) associated with echoplanar acquisition were characterized and modeled. Results from this fMRI study at 1.5 T indicate that the group-averaged HDR in left and right auditory cortex to acoustic imaging noise (duration of 46 ms) has an estimated peak magnitude of 0.29% (right) to 0.48% (left) signal change from baseline, peaks between 3 and 5 s after stimulus presentation, and returns to baseline and remains within the noise range approximately 8 s after stimulus presentation. PMID:19304477

  20. Human vision model for the objective evaluation of perceived image quality applied to MRI and image restoration

    NASA Astrophysics Data System (ADS)

    Salem, Kyle A.; Wilson, David L.

    2002-12-01

    We are developing a method to objectively quantify image quality and applying it to the optimization of interventional magnetic resonance imaging (iMRI). In iMRI, images are used for live-time guidance of interventional procedures such as the minimally invasive treatment of cancer. Hence, not only does one desire high quality images, but they must also be acquired quickly. In iMRI, images are acquired in the Fourier domain, or k-space, and this allows many creative ways to image quickly such as keyhole imaging where k-space is preferentially subsampled, yielding suboptimal images at very high frame rates. Other techniques include spiral, radial, and the combined acquisition technique. We have built a perceptual difference model (PDM) that incorporates various components of the human visual system. The PDM was validated using subjective image quality ratings by naive observers and task-based measures defined by interventional radiologists. Using the PDM, we investigated the effects of various imaging parameters on image quality and quantified the degradation due to novel imaging techniques. Results have provided significant information about imaging time versus quality tradeoffs aiding the MR sequence engineer. The PDM has also been used to evaluate other applications such as Dixon fat suppressed MRI and image restoration. In image restoration, the PDM has been used to evaluate the Generalized Minimal Residual (GMRES) image restoration method and to examine the ability to appropriately determine a stopping condition for such iterative methods. The PDM has been shown to be an objective tool for measuring image quality and can be used to determine the optimal methodology for various imaging applications.

  1. Patch-based image reconstruction for PET using prior-image derived dictionaries

    NASA Astrophysics Data System (ADS)

    Tahaei, Marzieh S.; Reader, Andrew J.

    2016-09-01

    In PET image reconstruction, regularization is often needed to reduce the noise in the resulting images. Patch-based image processing techniques have recently been successfully used for regularization in medical image reconstruction through a penalized likelihood framework. Re-parameterization within reconstruction is another powerful regularization technique in which the object in the scanner is re-parameterized using coefficients for spatially-extensive basis vectors. In this work, a method for extracting patch-based basis vectors from the subject’s MR image is proposed. The coefficients for these basis vectors are then estimated using the conventional MLEM algorithm. Furthermore, using the alternating direction method of multipliers, an algorithm for optimizing the Poisson log-likelihood while imposing sparsity on the parameters is also proposed. This novel method is then utilized to find sparse coefficients for the patch-based basis vectors extracted from the MR image. The results indicate the superiority of the proposed methods to patch-based regularization using the penalized likelihood framework.

  2. Dynamic contrast-enhanced MRI detects acute radiotherapy-induced alterations in mandibular microvasculature: prospective assessment of imaging biomarkers of normal tissue injury.

    PubMed

    2016-01-01

    Normal tissue toxicity is an important consideration in the continued development of more effective external beam radiotherapy (EBRT) regimens for head and neck tumors. The ability to detect EBRT-induced changes in mandibular bone vascularity represents a crucial step in decreasing potential toxicity. To date, no imaging modality has been shown to detect changes in bone vascularity in real time during treatment. Based on our institutional experience with multi-parametric MRI, we hypothesized that DCE-MRI can provide in-treatment information regarding EBRT-induced changes in mandibular vascularity. Thirty-two patients undergoing EBRT treatment for head and neck cancer were prospectively imaged prior to, mid-course, and following treatment. DCE-MRI scans were co-registered to dosimetric maps to correlate EBRT dose and change in mandibular bone vascularity as measured by Ktrans and Ve. DCE-MRI was able to detect dose-dependent changes in both Ktrans and Ve in a subset of patients. One patient who developed ORN during the study period demonstrated decreases in Ktrans and Ve following treatment completion. We demonstrate, in a prospective imaging trial, that DCE-MRI can detect dose-dependent alterations in mandibular bone vascularity during chemoradiotherapy, providing biomarkers that are physiological correlates of acute of acute mandibular vascular injury and recovery temporal kinetics. PMID:27499209

  3. Dynamic contrast-enhanced MRI detects acute radiotherapy-induced alterations in mandibular microvasculature: prospective assessment of imaging biomarkers of normal tissue injury

    PubMed Central

    Sandulache, Vlad C.; Hobbs, Brian P.; Mohamed, Abdallah S.R.; Frank, Steven J.; Song, Juhee; Ding, Yao; Ger, Rachel; Court, Laurence E.; Kalpathy-Cramer, Jayashree; Hazle, John D.; Wang, Jihong; Awan, Musaddiq J.; Rosenthal, David I.; Garden, Adam S.; Gunn, G. Brandon; Colen, Rivka R.; Elshafeey, Nabil; Elbanan, Mohamed; Hutcheson, Katherine A.; Lewin, Jan S.; Chambers, Mark S.; Hofstede, Theresa M.; Weber, Randal S.; Lai, Stephen Y.; Fuller, Clifton D.

    2016-01-01

    Normal tissue toxicity is an important consideration in the continued development of more effective external beam radiotherapy (EBRT) regimens for head and neck tumors. The ability to detect EBRT-induced changes in mandibular bone vascularity represents a crucial step in decreasing potential toxicity. To date, no imaging modality has been shown to detect changes in bone vascularity in real time during treatment. Based on our institutional experience with multi-parametric MRI, we hypothesized that DCE-MRI can provide in-treatment information regarding EBRT-induced changes in mandibular vascularity. Thirty-two patients undergoing EBRT treatment for head and neck cancer were prospectively imaged prior to, mid-course, and following treatment. DCE-MRI scans were co-registered to dosimetric maps to correlate EBRT dose and change in mandibular bone vascularity as measured by Ktrans and Ve. DCE-MRI was able to detect dose-dependent changes in both Ktrans and Ve in a subset of patients. One patient who developed ORN during the study period demonstrated decreases in Ktrans and Ve following treatment completion. We demonstrate, in a prospective imaging trial, that DCE-MRI can detect dose-dependent alterations in mandibular bone vascularity during chemoradiotherapy, providing biomarkers that are physiological correlates of acute of acute mandibular vascular injury and recovery temporal kinetics. PMID:27499209

  4. Imaging of the myocardium using (18)F-FDG-PET/MRI.

    PubMed

    Ferda, Jiří; Hromádka, Milan; Baxa, Jan

    2016-10-01

    The introduction of the integrated hybrid PET/MRI equipment creates the possibility to perform PET and MRI simultaneously. Depending on the clinical question, the metabolic conversion to glycolytic activity or beta-oxidation is performed before the application of FDG. Since FDG aids to evaluate the energetic metabolism of the myocytes and myocardial MRI reaches the imaging capabilities of perfusion and tissue characterization in the daily routine, FDG-PET/MRI looks to be a promising method of PET/MRI exploitation in cardiac imaging. When myocardial FDG uptake should be evaluated in association with the perfusion distribution, the cross-evaluation of FDG accumulation distribution and perfusion distribution pattern is necessary. The different scenarios may be used in the assessment of myocardium, the conversion to glycolytic activity is used in the imaging of the viable myocardium, but the glycolytic activity suppression might be used in the indications of the identification of injured myocardium by ischemia or inflammation. FDG-PET/MRI might aid to answer the clinical tasks according to the structure, current function and possibilities to improve the function in ischemic heart disease or to display the extent or activity of myocardial inflammation in sarcoidosis. The tight coupling between metabolism, perfusion and contractile function offers an opportunity for the simultaneous assessment of cardiac performance using one imaging modality. PMID:27470994

  5. PET/MRI: THE NEXT GENERATION OF MULTI-MODALITY IMAGING?

    PubMed Central

    Pichler, Bernd; Wehrl, Hans F; Kolb, Armin; Judenhofer, Martin S

    2009-01-01

    Multi-modal imaging is now well-established in routine clinical practice. Especially in the field of Nuclear Medicine, new PET installations are comprised almost exclusively of combined PET/CT scanners rather than PET-only systems. However, PET/CT has certain notable shortcomings, including the inability to perform simultaneous data acquisition and the significant radiation dose to the patient contributed by CT. MRI offers, compared to CT, better contrast among soft tissues as well as functional-imaging capabilities. Therefore, the combination of PET with MRI provides many advantages which go far beyond simply combining functional PET information with structural MRI information. Many technical challenges, including possible interference between these modalities, have to be solved when combining PET and MRI and various approaches have been adapted to resolving these issues. Here we present an overview of current working prototypes of combined PET/MRI scanners from different groups. In addition, besides PET/MR images of mice, the first such images of a rat PET/MR, acquired with the first commercial clinical PET/MRI scanner, are presented. The combination of PET and MR is a promising tool in pre-clinical research and will certainly progress to clinical application. PMID:18396179

  6. Imaging of the myocardium using (18)F-FDG-PET/MRI.

    PubMed

    Ferda, Jiří; Hromádka, Milan; Baxa, Jan

    2016-10-01

    The introduction of the integrated hybrid PET/MRI equipment creates the possibility to perform PET and MRI simultaneously. Depending on the clinical question, the metabolic conversion to glycolytic activity or beta-oxidation is performed before the application of FDG. Since FDG aids to evaluate the energetic metabolism of the myocytes and myocardial MRI reaches the imaging capabilities of perfusion and tissue characterization in the daily routine, FDG-PET/MRI looks to be a promising method of PET/MRI exploitation in cardiac imaging. When myocardial FDG uptake should be evaluated in association with the perfusion distribution, the cross-evaluation of FDG accumulation distribution and perfusion distribution pattern is necessary. The different scenarios may be used in the assessment of myocardium, the conversion to glycolytic activity is used in the imaging of the viable myocardium, but the glycolytic activity suppression might be used in the indications of the identification of injured myocardium by ischemia or inflammation. FDG-PET/MRI might aid to answer the clinical tasks according to the structure, current function and possibilities to improve the function in ischemic heart disease or to display the extent or activity of myocardial inflammation in sarcoidosis. The tight coupling between metabolism, perfusion and contractile function offers an opportunity for the simultaneous assessment of cardiac performance using one imaging modality.

  7. Semi-automatic delineation using weighted CT-MRI registered images for radiotherapy of nasopharyngeal cancer

    SciTech Connect

    Fitton, I.; Cornelissen, S. A. P.; Duppen, J. C.; Rasch, C. R. N.; Herk, M. van; Steenbakkers, R. J. H. M.; Peeters, S. T. H.; Hoebers, F. J. P.; Kaanders, J. H. A. M.; Nowak, P. J. C. M.

    2011-08-15

    Purpose: To develop a delineation tool that refines physician-drawn contours of the gross tumor volume (GTV) in nasopharynx cancer, using combined pixel value information from x-ray computed tomography (CT) and magnetic resonance imaging (MRI) during delineation. Methods: Operator-guided delineation assisted by a so-called ''snake'' algorithm was applied on weighted CT-MRI registered images. The physician delineates a rough tumor contour that is continuously adjusted by the snake algorithm using the underlying image characteristics. The algorithm was evaluated on five nasopharyngeal cancer patients. Different linear weightings CT and MRI were tested as input for the snake algorithm and compared according to contrast and tumor to noise ratio (TNR). The semi-automatic delineation was compared with manual contouring by seven experienced radiation oncologists. Results: A good compromise for TNR and contrast was obtained by weighing CT twice as strong as MRI. The new algorithm did not notably reduce interobserver variability, it did however, reduce the average delineation time by 6 min per case. Conclusions: The authors developed a user-driven tool for delineation and correction based a snake algorithm and registered weighted CT image and MRI. The algorithm adds morphological information from CT during the delineation on MRI and accelerates the delineation task.

  8. Tracing and quantification of pharmaceuticals using MR imaging and spectroscopy at clinical MRI system

    NASA Astrophysics Data System (ADS)

    Jeong, Eun-Kee; Liu, Xin; Shi, Xianfeng; Yu, Y. Bruce; Lu, Zeng-Rong

    2012-10-01

    Magnetic resonance imaging (MRI) and spectroscopy (MRS) is very powerful modality for imaging and localized investigation of biological tissue. Medical MRI measures nuclear magnetization of the water protons, which consists of 70 % of our body. MRI provides superior contrast among different soft tissues to all other existing medical imaging modalities, including ultrasound, X-ray CT, PET, and SPECT. In principle, MRI/S may be an ideal non-invasive tool for drug delivery research. However, because of its low sensitivity, a large dose is required for tracing pharmaceuticals. Therefore, its use for imaging of pharmaceuticals is very limited mostly to molecules that contain a paramagnetic metal ion, such as gadolinium (Gd3+) and manganese (Mn2+). The paramagnetic metal ion provides a large fluctuating magnetic field at the proton in the water molecule via a coordinate site. The measurement of local drug concentration is the first step for further quantification. Local concentration of the paramagnetic-ion based MRI contrast agent can be indirectly measured via the change in the water signal intensity. 19F MRI/S of fluorinated complex may be an option for drug delivery and tracing agent, because the fluorinated molecule may be directly detected due to its large magnetic moment (94 % of proton) and 100 % abundance.

  9. Level-set segmentation of pulmonary nodules in megavolt electronic portal images using a CT prior

    SciTech Connect

    Schildkraut, J. S.; Prosser, N.; Savakis, A.; Gomez, J.; Nazareth, D.; Singh, A. K.; Malhotra, H. K.

    2010-11-15

    Purpose: Pulmonary nodules present unique problems during radiation treatment due to nodule position uncertainty that is caused by respiration. The radiation field has to be enlarged to account for nodule motion during treatment. The purpose of this work is to provide a method of locating a pulmonary nodule in a megavolt portal image that can be used to reduce the internal target volume (ITV) during radiation therapy. A reduction in the ITV would result in a decrease in radiation toxicity to healthy tissue. Methods: Eight patients with nonsmall cell lung cancer were used in this study. CT scans that include the pulmonary nodule were captured with a GE Healthcare LightSpeed RT 16 scanner. Megavolt portal images were acquired with a Varian Trilogy unit equipped with an AS1000 electronic portal imaging device. The nodule localization method uses grayscale morphological filtering and level-set segmentation with a prior. The treatment-time portion of the algorithm is implemented on a graphical processing unit. Results: The method was retrospectively tested on eight cases that include a total of 151 megavolt portal image frames. The method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases. The treatment phase portion of the method has a subsecond execution time that makes it suitable for near-real-time nodule localization. Conclusions: A method was developed to localize a pulmonary nodule in a megavolt portal image. The method uses the characteristics of the nodule in a prior CT scan to enhance the nodule in the portal image and to identify the nodule region by level-set segmentation. In a retrospective study, the method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases studied.

  10. Three-dimensional reconstruction of registered and fused Chinese Visible Human and patient MRI images.

    PubMed

    Li, L; Liu, Y X; Song, Z J

    2006-04-01

    Radiological images are commonly used as important tools in medical diagnoses and treatment. Different modalities of medical images provide uniquely different content. Hence, it is natural and desirable to combine different image modalities to obtain additional new information to enhance clinical assessment. However, given the current technology, radiological images are not always sufficiently informative to permit diagnosis and treatment. In order to address this problem, we fused selected portions of the Chinese Visible Human (CVH) dataset with MRI images from a patient. Specifically, we segmented the caudate nucleus, the lentiform nucleus, and the thalamus in the CVH dataset and then registered and fused this dataset with corresponding MRI images using both rigid and nonrigid registration techniques. After rigid and nonrigid registration, the CVH and MRI images largely coincided with each other. The shape, relationship, and position of focal areas and neural structures were clearly displayed. Using volume and surface rendering, these images were three-dimensionally reconstructed to display the neural structures of interest within the brain. These structures can be rotated at will and observed from different angles. Our research indicates that the fusion of CVH and patients' MRI images can enhance the amount of neural information available to physicians and lay a foundation for the clinical use of the CVH dataset. PMID:16506210

  11. Clinical Utility of Positron Emission Tomography Magnetic Resonance Imaging (PET-MRI) in Gastrointestinal Cancers

    PubMed Central

    Matthews, Robert; Choi, Minsig

    2016-01-01

    Anatomic imaging utilizing both CT (computed tomography) and MRI (magnetic resonance imaging) limits the assessment of cancer metastases in lymph nodes and distant organs while functional imaging like PET (positron emission tomography) scan has its limitation in spatial resolution capacity. Hybrid imaging utilizing PET-CT and PET-MRI are novel imaging modalities that are changing the current landscape in cancer diagnosis, staging, and treatment response. MRI has shown to have higher sensitivity in soft tissue, head and neck pathology, and pelvic disease, as well as, detecting small metastases in the liver and bone compared to CT. Combining MRI with PET allows for detection of metastases that may have been missed with current imaging modalities. In this review, we will examine the clinical utility of FDG PET-MRI in the diagnosis and staging of gastrointestinal cancers with focus on esophageal, stomach, colorectal, and pancreatic cancers. We will also explore its role in treatment response and future directions associated with it. PMID:27618106

  12. Clinical Utility of Positron Emission Tomography Magnetic Resonance Imaging (PET-MRI) in Gastrointestinal Cancers.

    PubMed

    Matthews, Robert; Choi, Minsig

    2016-01-01

    Anatomic imaging utilizing both CT (computed tomography) and MRI (magnetic resonance imaging) limits the assessment of cancer metastases in lymph nodes and distant organs while functional imaging like PET (positron emission tomography) scan has its limitation in spatial resolution capacity. Hybrid imaging utilizing PET-CT and PET-MRI are novel imaging modalities that are changing the current landscape in cancer diagnosis, staging, and treatment response. MRI has shown to have higher sensitivity in soft tissue, head and neck pathology, and pelvic disease, as well as, detecting small metastases in the liver and bone compared to CT. Combining MRI with PET allows for detection of metastases that may have been missed with current imaging modalities. In this review, we will examine the clinical utility of FDG PET-MRI in the diagnosis and staging of gastrointestinal cancers with focus on esophageal, stomach, colorectal, and pancreatic cancers. We will also explore its role in treatment response and future directions associated with it. PMID:27618106

  13. Intraoperative MRI and functional mapping.

    PubMed

    Gasser, Thomas; Szelenyi, Andrea; Senft, Christian; Muragaki, Yoshihiro; Sandalcioglu, I Erol; Sure, Ulrich; Nimsky, Christopher; Seifert, Volker

    2011-01-01

    The integration of functional and anatomical data into neuronavigation is an established standard of care in many neurosurgical departments. Yet, this method has limitations as in most cases the data are acquired prior to surgery. Due to brain-shift the accurate presentation of functional as well as anatomical structures declines in the course of surgery. In consequence, the acquisition of information during surgery about the brain's current functional state is of specific interest. The advancement of imaging technologies (e.g. fMRI, MEG, Intraoperative Optical Intrinsic Signal Imaging--IOIS) and neurophysiological techniques and the advent of intraoperative MRI all had a major impact on neurosurgery. The combination of modalities such as neurophysiology and intraoperative MRI (ioMRI), as well as the acquisition of functional MRI during surgery (ifMRI) are in the focus of this work. Especially the technical aspects and safety issues are elucidated.

  14. Electrical tissue property imaging using MRI at dc and Larmor frequency

    NASA Astrophysics Data System (ADS)

    Seo, Jin Keun; Kim, Dong-Hyun; Lee, Joonsung; In Kwon, Oh; Sajib, Saurav Z. K.; Woo, Eung Je

    2012-08-01

    Cross-sectional imaging of conductivity and permittivity distributions inside the human body has been actively investigated in impedance imaging areas such as electrical impedance tomography (EIT) and magnetic induction tomography (MIT). Since the conductivity and permittivity values exhibit frequency-dependent changes, it is worthwhile to perform spectroscopic imaging from almost dc to hundreds of MHz. To probe the human body, we may inject current using surface electrodes or induce current using external coils. In EIT and MIT, measured data are only available on the boundary or exterior of the body unless we invasively place sensors inside the body. Their image reconstruction problems are nonlinear and ill-posed to result in images with a relatively low spatial resolution. Noting that an MRI scanner can noninvasively measure magnetic fields inside the human body, electrical tissue property imaging methods using MRI have lately been proposed. Magnetic resonance EIT (MREIT) performs conductivity imaging at dc or below 1 kHz by externally injecting current into the human body and measuring induced internal magnetic flux density data using an MRI scanner. Magnetic resonance electrical property tomography (MREPT) produces both conductivity and permittivity images at the Larmor frequency of an MRI scanner based on B1-mapping techniques. Since internal data are only available in MREIT and MREPT, we may formulate well-posed inverse problems for image reconstructions. To develop related imaging techniques, we should clearly understand the basic principles of MREIT and MREPT, which are based on coupled physics of bioelectromagnetism and MRI as well as associated mathematical methods. In this paper, we describe the physical principles of MREIT and MREPT in a unified way and associate measurable quantities with the conductivity and permittivity. Clarifying the key relations among them, we examine existing image reconstruction algorithms to reveal their capabilities and

  15. An Improved Total Variation Minimization Method Using Prior Images and Split-Bregman Method in CT Reconstruction

    PubMed Central

    2016-01-01

    Compressive Sensing (CS) theory has great potential for reconstructing Computed Tomography (CT) images from sparse-views projection data and Total Variation- (TV-) based CT reconstruction method is very popular. However, it does not directly incorporate prior images into the reconstruction. To improve the quality of reconstructed images, this paper proposed an improved TV minimization method using prior images and Split-Bregman method in CT reconstruction, which uses prior images to obtain valuable previous information and promote the subsequent imaging process. The images obtained asynchronously were registered via Locally Linear Embedding (LLE). To validate the method, two studies were performed. Numerical simulation using an abdomen phantom has been used to demonstrate that the proposed method enables accurate reconstruction of image objects under sparse projection data. A real dataset was used to further validate the method. PMID:27689076

  16. An Improved Total Variation Minimization Method Using Prior Images and Split-Bregman Method in CT Reconstruction

    PubMed Central

    2016-01-01

    Compressive Sensing (CS) theory has great potential for reconstructing Computed Tomography (CT) images from sparse-views projection data and Total Variation- (TV-) based CT reconstruction method is very popular. However, it does not directly incorporate prior images into the reconstruction. To improve the quality of reconstructed images, this paper proposed an improved TV minimization method using prior images and Split-Bregman method in CT reconstruction, which uses prior images to obtain valuable previous information and promote the subsequent imaging process. The images obtained asynchronously were registered via Locally Linear Embedding (LLE). To validate the method, two studies were performed. Numerical simulation using an abdomen phantom has been used to demonstrate that the proposed method enables accurate reconstruction of image objects under sparse projection data. A real dataset was used to further validate the method.

  17. Diagnoses in Pediatric Patients With Magnetic Resonance Imaging (MRI) Lesions Suspicious for Demyelination.

    PubMed

    Sweeney, Michael L; Kukreja, Marcia; Horn, Paul S; Standridge, Shannon M

    2015-10-01

    Magnetic resonance imaging (MRI) studies of the brain in pediatric patients frequently show abnormal white matter lesions, which may be concerning for demyelinating disease. This study aimed to determine the proportion of pediatric patients who have MRI lesions concerning for demyelinating disease at presentation and ultimately are diagnosed with a primary central nervous system demyelinating disease. A retrospective chart review was performed on MRI reports of patients who underwent imaging evaluation at a single tertiary pediatric hospital. Of 299 patients identified, 192 presented with acute neurologic complaints. In this group, ≥ 5 discrete lesions, African American race, and having brain stem, thalamic, cerebellar, or optic nerve lesions was associated with the patient being diagnosed with a disease that required further treatment. The other 107 patients underwent MRI for other indications. Among these subjects, having lesions within the corpus callosum or cerebellum was associated with being diagnosed with a disease requiring further treatment.

  18. In-vivo human brain molecular imaging with a brain-dedicated PET/MRI system.

    PubMed

    Cho, Zang Hee; Son, Young Don; Choi, Eun Jung; Kim, Hang Keun; Kim, Jeong Hee; Lee, Sang Yoon; Ogawa, Seiji; Kim, Young Bo

    2013-02-01

    Advances in the new-generation of ultra-high-resolution, brain-dedicated positron emission tomography-magnetic resonance imaging (PET/MRI) systems have begun to provide many interesting insights into the molecular dynamics of the brain. First, the finely delineated structural information from ultra-high-field MRI can help us to identify accurate landmark structures, thereby making it easier to locate PET activation sites that are anatomically well-correlated with metabolic or ligand-specific organs in the neural structures in the brain. This synergistic potential of PET/MRI imaging is discussed in terms of neuroscience and neurological research from both translational and basic research perspectives. Experimental results from the hippocampus, thalamus, and brainstem obtained with (18)F-fluorodeoxyglucose and (11)C-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)benzonitrile are used to demonstrate the potential of this new brain PET/MRI system.

  19. Congruent MRI and near-infrared spectroscopy for functional and structural imaging of tumors.

    PubMed

    Gulsen, Gultekin; Yu, Hon; Wang, Jun; Nalcioglu, Orhan; Merritt, Sean; Bevilacqua, Frederic; Durkin, Anthony J; Cuccia, David J; Lanning, Ryan; Tromberg, Bruce J

    2002-12-01

    We present a combined near-infrared diffuse optical spectroscopy (DOS) and Magnetic Resonance Imaging (MRI) system for the study of animal model tumors. A combined broadband steady-state and frequency domain optical spectroscopy apparatus was integrated with the MRI. The physiological properties of tissue rendered by MRI, including vascular volume fraction and water, were compared with chromophore concentrations as determined from the parameters obtained by optical measurements. DOS measurements provided oxy-hemoglobin, deoxy-hemoglobin, and water concentration locally in tumors. A method for co-registration of the information obtained by both modalities was developed. Using Monte Carlo simulations, the optically sampled volume was superimposed on the MR images, illustrating which tissue structure was probed optically. Finally, two optical contrast agents, indocyanine green (ICG) and methylene blue (MB), were employed and their kinetics were measured by DOS system from different locations on the tumor and compared with Gd-DTPA enhancement maps obtained from MRI.

  20. Interpreting Intervention Induced Neuroplasticity with fMRI: The Case for Multimodal Imaging Strategies

    PubMed Central

    Reid, Lee B.; Boyd, Roslyn N.; Cunnington, Ross; Rose, Stephen E.

    2016-01-01

    Direct measurement of recovery from brain injury is an important goal in neurorehabilitation, and requires reliable, objective, and interpretable measures of changes in brain function, referred to generally as “neuroplasticity.” One popular imaging modality for measuring neuroplasticity is task-based functional magnetic resonance imaging (t-fMRI). In the field of neurorehabilitation, however, assessing neuroplasticity using t-fMRI presents a significant challenge. This commentary reviews t-fMRI changes commonly reported in patients with cerebral palsy or acquired brain injuries, with a focus on studies of motor rehabilitation, and discusses complexities surrounding their interpretations. Specifically, we discuss the difficulties in interpreting t-fMRI changes in terms of their underlying causes, that is, differentiating whether they reflect genuine reorganisation, neurological restoration, compensation, use of preexisting redundancies, changes in strategy, or maladaptive processes. Furthermore, we discuss the impact of heterogeneous disease states and essential t-fMRI processing steps on the interpretability of activation patterns. To better understand therapy-induced neuroplastic changes, we suggest that researchers utilising t-fMRI consider concurrently acquiring information from an additional modality, to quantify, for example, haemodynamic differences or microstructural changes. We outline a variety of such supplementary measures for investigating brain reorganisation and discuss situations in which they may prove beneficial to the interpretation of t-fMRI data. PMID:26839711

  1. Shape priors for segmentation of the cervix region within uterine cervix images.

    PubMed

    Lotenberg, Shelly; Gordon, Shiri; Greenspan, Hayit

    2009-06-01

    The work focuses on a unique medical repository of digital uterine cervix images ("cervigrams") collected by the National Cancer Institute (NCI), National Institute of Health, in longitudinal multiyear studies. NCI together with the National Library of Medicine is developing a unique web-based database of the digitized cervix images to study the evolution of lesions related to cervical cancer. Tools are needed for the automated analysis of the cervigram content to support the cancer research. In recent works, a multistage automated system for segmenting and labeling regions of medical and anatomical interest within the cervigrams was developed. The current paper concentrates on incorporating prior-shape information in the cervix region segmentation task. In accordance with the fact that human experts mark the cervix region as circular or elliptical, two shape models (and corresponding methods) are suggested. The shape models are embedded within an active contour framework that relies on image features. Experiments indicate that incorporation of the prior shape information augments previous results.

  2. Shape priors for segmentation of the cervix region within uterine cervix images

    NASA Astrophysics Data System (ADS)

    Lotenberg, Shelly; Gordon, Shiri; Greenspan, Hayit

    2008-03-01

    The work focuses on a unique medical repository of digital Uterine Cervix images ("Cervigrams") collected by the National Cancer Institute (NCI), National Institute of Health, in longitudinal multi-year studies. NCI together with the National Library of Medicine is developing a unique web-based database of the digitized cervix images to study the evolution of lesions related to cervical cancer. Tools are needed for the automated analysis of the cervigram content to support the cancer research. In recent works, a multi-stage automated system for segmenting and labeling regions of medical and anatomical interest within the cervigrams was developed. The current paper concentrates on incorporating prior-shape information in the cervix region segmentation task. In accordance with the fact that human experts mark the cervix region as circular or elliptical, two shape models (and corresponding methods) are suggested. The shape models are embedded within an active contour framework that relies on image features. Experiments indicate that incorporation of the prior shape information augments previous results.

  3. 2D dose distribution images of a hybrid low field MRI-γ detector

    NASA Astrophysics Data System (ADS)

    Abril, A.; Agulles-Pedrós, L.

    2016-07-01

    The proposed hybrid system is a combination of a low field MRI and dosimetric gel as a γ detector. The readout system is based on the polymerization process induced by the gel radiation. A gel dose map is obtained which represents the functional part of hybrid image alongside with the anatomical MRI one. Both images should be taken while the patient with a radiopharmaceutical is located inside the MRI system with a gel detector matrix. A relevant aspect of this proposal is that the dosimetric gel has never been used to acquire medical images. The results presented show the interaction of the 99mTc source with the dosimetric gel simulated in Geant4. The purpose was to obtain the planar γ 2D-image. The different source configurations are studied to explore the ability of the gel as radiation detector through the following parameters; resolution, shape definition and radio-pharmaceutical concentration.

  4. Multispectral image classification of MRI data using an empirically-derived clustering algorithm

    SciTech Connect

    Horn, K.M.; Osbourn, G.C.; Bouchard, A.M.; Sanders, J.A. |

    1998-08-01

    Multispectral image analysis of magnetic resonance imaging (MRI) data has been performed using an empirically-derived clustering algorithm. This algorithm groups image pixels into distinct classes which exhibit similar response in the T{sub 2} 1st and 2nd-echo, and T{sub 1} (with ad without gadolinium) MRI images. The grouping is performed in an n-dimensional mathematical space; the n-dimensional volumes bounding each class define each specific tissue type. The classification results are rendered again in real-space by colored-coding each grouped class of pixels (associated with differing tissue types). This classification method is especially well suited for class volumes with complex boundary shapes, and is also expected to robustly detect abnormal tissue classes. The classification process is demonstrated using a three dimensional data set of MRI scans of a human brain tumor.

  5. Effects of magnetic resonance imaging (MRI) on the formation of mouse dentin and bone

    SciTech Connect

    Kwong-Hing, A.; Sandhu, H.S.; Prato, F.S.; Frappier, J.R.; Kavaliers, M. )

    1989-10-01

    The effects of magnetic resonance imaging (MRI) on dentin and bone formation in mice were examined using standard autoradiographic and liquid scintillation procedures. It was observed that exposure to a standard 23.2 min clinical multislice MRI (0.15T) procedure caused a significant increase in the synthesis of the collagenous matrix of dentin in the incisors of mice. There were no significant effects on alveolar and tibial bone matrix synthesis. These results suggest that the magnetic fields associated with MRI can affect the activity of cells and/or tissues that are involved in rapid synthetic activity.

  6. High-resolution MRI of spinal cords by compressive sensing parallel imaging.

    PubMed

    Peng Li; Xiangdong Yu; Griffin, Jay; Levine, Jonathan M; Jim Ji

    2015-08-01

    Spinal Cord Injury (SCI) is a common injury due to diseases or accidents. Noninvasive imaging methods play a critical role in diagnosing SCI and monitoring the response to therapy. Magnetic Resonance Imaging (MRI), by the virtue of providing excellent soft tissue contrast, is the most promising imaging method for this application. However, spinal cord has a very small cross-section, which needs high-resolution images for better visualization and diagnosis. Acquiring high-resolution spinal cord MRI images requires long acquisition time due to the physical and physiological constraints. Moreover, long acquisition time makes MRI more susceptible to motion artifacts. In this paper, we studied the application of compressive sensing (CS) and parallel imaging to achieve high-resolution imaging from sparsely sampled and reduced k-space data acquired by parallel receive arrays. In particular, the studies are limited to the effects of 2D Cartesian sampling with different subsampling schemes and reduction factors. The results show that compressive sensing parallel MRI has the potential to provide high-resolution images of the spinal cord in 1/3 of the acquisition time required by the conventional methods.

  7. MRI-guided brain PET image filtering and partial volume correction

    NASA Astrophysics Data System (ADS)

    Yan, Jianhua; Chu-Shern Lim, Jason; Townsend, David W.

    2015-02-01

    Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and 18F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data.

  8. SU-E-J-217: Multiparametric MR Imaging of Cranial Tumors On a Dedicated 1.0T MR Simulator Prior to Stereotactic Radiosurgery

    SciTech Connect

    Wen, N; Glide-Hurst, C; Liu, M; Hearshen, D; Brown, S; Siddiqui, S; Chetty, I

    2015-06-15

    Purpose: Quantitative magnetic resonance imaging (MRI) of cranial lesions prior to stereotactic radiosurgery (SRS) may improve treatment planning and provide potential prognostic value. The practicality and logistics of acquiring advanced multiparametric MRI sequences to measure vascular and cellular properties of cerebral tumors are explored on a 1.0 Tesla MR Simulator. Methods: MR simulation was performed immediately following routine CT simulation on a 1T MR Simulator. MR sequences used were in the order they were performed: T2-Weighted Turbo Spin Echo (T2W-TSE), T2 FLAIR, Diffusion-weighted (DWI, b = 0, 800 to generate an apparent diffusion coefficient (ADC) map), 3D T1-Weighted Fast Field Echo (T1W-FFE), Dynamic Contrast Enhanced (DCE) and Post Gadolinium Contrast Enhanced 3D T1W-FFE images. T1 pre-contrast values was generated by acquiring six different flip angles. The arterial input function was derived from arterial pixels in the perfusion images selected manually. The extended Tofts model was used to generate the permeability maps. Routine MRI scans took about 30 minutes to complete; the additional scans added 12 minutes. Results: To date, seven patients with cerebral tumors have been imaged and tumor physiology characterized. For example, on a glioblastoma patient, the volume contoured on T1 Gd images, ADC map and the pharmacokinetic map (Ktrans) were 1.9, 1.4, and 1.5 cc respectively with strong spatial correlation. The mean ADC value of the entire volume was 1141 μm2/s while the value in the white matter was 811 μm2/s. The mean value of Ktrans was 0.02 min-1 in the tumor volume and 0.00 in the normal white matter. Conclusion: Our initial results suggest that multiparametric MRI sequences may provide a more quantitative evaluation of vascular and tumor properties. Implementing functional imaging during MR-SIM may be particularly beneficial in assessing tumor extent, differentiating radiation necrosis from tumor recurrence, and establishing reliable

  9. Optimized time-resolved imaging of contrast kinetics (TRICKS) in dynamic contrast-enhanced MRI after peptide receptor radionuclide therapy in small animal tumor models.

    PubMed

    Haeck, Joost; Bol, Karin; Bison, Sander; van Tiel, Sandra; Koelewijn, Stuart; de Jong, Marion; Veenland, Jifke; Bernsen, Monique

    2015-01-01

    Anti-tumor efficacy of targeted peptide-receptor radionuclide therapy (PRRT) relies on several factors, including functional tumor vasculature. Little is known about the effect of PRRT on tumor vasculature. With dynamic contrast-enhanced (DCE-) MRI, functional vasculature is imaged and quantified using contrast agents. In small animals DCE-MRI is a challenging application. We optimized a clinical sequence for fast hemodynamic acquisitions, time-resolved imaging of contrast kinetics (TRICKS), to obtain DCE-MRI images at both high spatial and high temporal resolution in mice and rats. Using TRICKS, functional vasculature was measured prior to PRRT and longitudinally to investigate the effect of treatment on tumor vascular characteristics. Nude mice bearing H69 tumor xenografts and rats bearing syngeneic CA20948 tumors were used to study perfusion following PRRT administration with (177) lutetium octreotate. Both semi-quantitative and quantitative parameters were calculated. Treatment efficacy was measured by tumor-size reduction. Optimized TRICKS enabled MRI at 0.032 mm(3) voxel size with a temporal resolution of less than 5 s and large volume coverage, a substantial improvement over routine pre-clinical DCE-MRI studies. Tumor response to therapy was reflected in changes in tumor perfusion/permeability parameters. The H69 tumor model showed pronounced changes in DCE-derived parameters following PRRT. The rat CA20948 tumor model showed more heterogeneity in both treatment outcome and perfusion parameters. TRICKS enabled the acquisition of DCE-MRI at both high temporal resolution (Tres ) and spatial resolutions relevant for small animal tumor models. With the high Tres enabled by TRICKS, accurate pharmacokinetic data modeling was feasible. DCE-MRI parameters revealed changes over time and showed a clear relationship between tumor size and Ktrans . PMID:25995102

  10. Optimized time-resolved imaging of contrast kinetics (TRICKS) in dynamic contrast-enhanced MRI after peptide receptor radionuclide therapy in small animal tumor models.

    PubMed

    Haeck, Joost; Bol, Karin; Bison, Sander; van Tiel, Sandra; Koelewijn, Stuart; de Jong, Marion; Veenland, Jifke; Bernsen, Monique

    2015-01-01

    Anti-tumor efficacy of targeted peptide-receptor radionuclide therapy (PRRT) relies on several factors, including functional tumor vasculature. Little is known about the effect of PRRT on tumor vasculature. With dynamic contrast-enhanced (DCE-) MRI, functional vasculature is imaged and quantified using contrast agents. In small animals DCE-MRI is a challenging application. We optimized a clinical sequence for fast hemodynamic acquisitions, time-resolved imaging of contrast kinetics (TRICKS), to obtain DCE-MRI images at both high spatial and high temporal resolution in mice and rats. Using TRICKS, functional vasculature was measured prior to PRRT and longitudinally to investigate the effect of treatment on tumor vascular characteristics. Nude mice bearing H69 tumor xenografts and rats bearing syngeneic CA20948 tumors were used to study perfusion following PRRT administration with (177) lutetium octreotate. Both semi-quantitative and quantitative parameters were calculated. Treatment efficacy was measured by tumor-size reduction. Optimized TRICKS enabled MRI at 0.032 mm(3) voxel size with a temporal resolution of less than 5 s and large volume coverage, a substantial improvement over routine pre-clinical DCE-MRI studies. Tumor response to therapy was reflected in changes in tumor perfusion/permeability parameters. The H69 tumor model showed pronounced changes in DCE-derived parameters following PRRT. The rat CA20948 tumor model showed more heterogeneity in both treatment outcome and perfusion parameters. TRICKS enabled the acquisition of DCE-MRI at both high temporal resolution (Tres ) and spatial resolutions relevant for small animal tumor models. With the high Tres enabled by TRICKS, accurate pharmacokinetic data modeling was feasible. DCE-MRI parameters revealed changes over time and showed a clear relationship between tumor size and Ktrans .

  11. Three-dimensional, in vivo MRI with self-gating and image coregistration in the mouse.

    PubMed

    Nieman, Brian J; Szulc, Kamila U; Turnbull, Daniel H

    2009-05-01

    Motion during magnetic resonance imaging (MRI) scans routinely results in undesirable image artifact or blurring. Since high-resolution, three-dimensional (3D) imaging of the mouse requires long scan times for satisfactory signal-to-noise ratio (SNR) and image quality, motion-related artifacts are likely over much of the body and limit applications of mouse MRI. In this investigation, we explored the use of self-gated imaging methods and image coregistration for improving image quality in the presence of motion. Self-gated signal results from a modified 3D gradient-echo sequence showed detection of periodic respiratory and cardiac motion in the adult mouse-with excellent comparison to traditional measurements, sensitivity to respiration-induced tissue changes in the brain, and even detection of embryonic cardiac motion in utero. Serial image coregistration with rapidly-acquired, low-SNR volumes further enabled detection and correction of bulk changes in embryo location during in utero imaging sessions and subsequent reconstruction of high-quality images. These methods, in combination, are shown to expand the range of applications for 3D mouse MRI, enabling late-stage embryonic heart imaging and introducing the possibility of longitudinal developmental studies from embryonic stages through adulthood.

  12. High resolution MRI imaging at 1. 5T using surface coils

    SciTech Connect

    Blinder, R.A.; Herfkens, R.J.; Coleman, R.E.; Johnson, G.A.; Schenck, J.F.; Hart, H.R. Jr.; Foster, T.H.; Edelstein, W.A.

    1985-05-01

    The potential utility of high resolution MRI imaging in various pathologic conditions was explored. As the voxel size of MRI images is decreased the signal per pixel diminishes due to the geometric decrease in volume. In very high resolution images the signal can be small enough to be obscured by Johnson noise. High magnetic field strength (1.5T) coupled with surface coil imaging increases the signal to noise ratio. The surface coils used were single turn coils with diameters of 6 or 11 cm depending on the body part being imaged. A ''clam shell'' crossed coil was used for imaging the knees. Using a 1.5T prototype MRI imaging system we have obtained images with 14.5 cm field of view that are 256 by 256 pixels with a slice thickness of 3 mm. Good signal to noise is obtained using 2DTF imaging with only 2 excitations per phase encoding step (1 average). Images obtained of peripheral joints demonstrate articular cartilage, ligamentous structures, and trabeculae in medullary bone. These exams have demonstrated the changes of rheumatoid arthritis, and the extent of neoplastic involvement in bone. Images of the temporomandibular joint and the neck have been obtained. Parathyroid adenomas have been identified. Surface coil imaging and high magnetic fields allow for high resolution MRI imaging of various anatomic structures. Good signal to noise can be accomplished without extensive signal averaging so that reasonable imaging times and throughput can be realized with voxel dimensions of 0.6 x 0.6 x 3mm.

  13. Volumetric BOLD fMRI simulation: from neurovascular coupling to multivoxel imaging

    PubMed Central

    2012-01-01

    Background The blood oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI) modality has been numerically simulated by calculating single voxel signals. However, the observation on single voxel signals cannot provide information regarding the spatial distribution of the signals. Specifically, a single BOLD voxel signal simulation cannot answer the fundamental question: is the magnetic resonance (MR) image a replica of its underling magnetic susceptibility source? In this paper, we address this problem by proposing a multivoxel volumetric BOLD fMRI simulation model and a susceptibility expression formula for linear neurovascular coupling process, that allow us to examine the BOLD fMRI procedure from neurovascular coupling to MR image formation. Methods Since MRI technology only senses the magnetism property, we represent a linear neurovascular-coupled BOLD state by a magnetic susceptibility expression formula, which accounts for the parameters of cortical vasculature, intravascular blood oxygenation level, and local neuroactivity. Upon the susceptibility expression of a BOLD state, we carry out volumetric BOLD fMRI simulation by calculating the fieldmap (established by susceptibility magnetization) and the complex multivoxel MR image (by intravoxel dephasing). Given the predefined susceptibility source and the calculated complex MR image, we compare the MR magnitude (phase, respectively) image with the predefined susceptibility source (the calculated fieldmap) by spatial correlation. Results The spatial correlation between the MR magnitude image and the magnetic susceptibility source is about 0.90 for the settings of TE = 30 ms, B0 = 3 T, voxel size = 100 micron, vessel radius = 3 micron, and blood volume fraction = 2%. Using these parameters value, the spatial correlation between the MR phase image and the susceptibility-induced fieldmap is close to 1.00. Conclusion Our simulation results show that the MR magnitude image is not an exact

  14. Summary statistics from training images as prior information in probabilistic inversion

    NASA Astrophysics Data System (ADS)

    Lochbühler, Tobias; Vrugt, Jasper A.; Sadegh, Mojtaba; Linde, Niklas

    2015-04-01

    A strategy is presented to incorporate prior information from conceptual geological models in probabilistic inversion of geophysical data. The conceptual geological models are represented by multiple-point statistics training images (TIs) featuring the expected lithological units and structural patterns. Information from an ensemble of TI realizations is used in two different ways. First, dominant modes are identified by analysis of the frequency content in the realizations, which drastically reduces the model parameter space in the frequency-amplitude domain. Second, the distributions of global, summary metrics (e.g. model roughness) are used to formulate a prior probability density function. The inverse problem is formulated in a Bayesian framework and the posterior pdf is sampled using Markov chain Monte Carlo simulation. The usefulness and applicability of this method is demonstrated on two case studies in which synthetic crosshole ground-penetrating radar traveltime data are inverted to recover 2-D porosity fields. The use of prior information from TIs significantly enhances the reliability of the posterior models by removing inversion artefacts and improving individual parameter estimates. The proposed methodology reduces the ambiguity inherent in the inversion of high-dimensional parameter spaces, accommodates a wide range of summary statistics and geophysical forward problems.

  15. Single element ultrasonic imaging of limb geometry: an in-vivo study with comparison to MRI

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Fincke, Jonathan R.; Anthony, Brian W.

    2016-04-01

    Despite advancements in medical imaging, current prosthetic fitting methods remain subjective, operator dependent, and non-repeatable. The standard plaster casting method relies on prosthetist experience and tactile feel of the limb to design the prosthetic socket. Often times, many fitting iterations are required to achieve an acceptable fit. Use of improper socket fittings can lead to painful pathologies including neuromas, inflammation, soft tissue calcification, and pressure sores, often forcing the wearer to into a wheelchair and reducing mobility and quality of life. Computer software along with MRI/CT imaging has already been explored to aid the socket design process. In this paper, we explore the use of ultrasound instead of MRI/CT to accurately obtain the underlying limb geometry to assist the prosthetic socket design process. Using a single element ultrasound system, multiple subjects' proximal limbs were imaged using 1, 2.25, and 5 MHz single element transducers. Each ultrasound transducer was calibrated to ensure acoustic exposure within the limits defined by the FDA. To validate image quality, each patient was also imaged in an MRI. Fiducial markers visible in both MRI and ultrasound were used to compare the same limb cross-sectional image for each patient. After applying a migration algorithm, B-mode ultrasound cross-sections showed sufficiently high image resolution to characterize the skin and bone boundaries along with the underlying tissue structures.

  16. gr-MRI: A software package for magnetic resonance imaging using software defined radios.

    PubMed

    Hasselwander, Christopher J; Cao, Zhipeng; Grissom, William A

    2016-09-01

    The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately $2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR's ability to generate frequency-swept RF waveforms was validated and compared to the scanner's commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs. PMID:27394165

  17. gr-MRI: A software package for magnetic resonance imaging using software defined radios.

    PubMed

    Hasselwander, Christopher J; Cao, Zhipeng; Grissom, William A

    2016-09-01

    The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately $2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR's ability to generate frequency-swept RF waveforms was validated and compared to the scanner's commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs.

  18. gr-MRI: A software package for magnetic resonance imaging using software defined radios

    NASA Astrophysics Data System (ADS)

    Hasselwander, Christopher J.; Cao, Zhipeng; Grissom, William A.

    2016-09-01

    The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5 Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately 2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR's ability to generate frequency-swept RF waveforms was validated and compared to the scanner's commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500 kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs.

  19. A comparison of the psychological burden of PET/MRI and PET/CT scans and association to initial state anxiety and previous imaging experiences

    PubMed Central

    Neriman, D; Hoath, J; Millner, L; Endozo, R; Azzopardi, G; O'Meara, C; Bomanji, J; Groves, A M

    2015-01-01

    Objective: To investigate the level of psychological burden experienced by patients undergoing positron emission tomography (PET)/MRI scanning compared with PET/CT. Methods: 100 adult patients referred for PET/CT and underwent PET/MRI scanning were eligible. Initial state, psychological burden of PET/CT and PET/MRI, scan satisfaction and preference were assessed using a purpose-designed questionnaire, comprising 61 five-point Likert scale questions and a three-point tick box question indicating preference between PET/CT and PET/MRI. State anxiety was assessed using the state portion of the State Trait Anxiety Inventory. Wilcoxon signed-rank tests compared psychological burden experienced by participants following PET/CT and PET/MRI scan. Results: A greater level of psychological burden was experienced by patients during PET/MRI than PET/CT p ≤ 0.001, consistent with patients' preference for PET/CT over PET/MRI (p = 0.013). There was a significant relationship between PET/CT psychological burden and initial state (r = 0.386, p ≤ 0.001). No significant relationship was identified between Initial state and psychological burden of PET MRI (r = −0.089; p = 217). There was a significant relationship between psychological burden of PET/CT and PET/MRI (r = 0.354; p = 0.001). Conclusion: Patients' experience increased psychological burden during PET/MRI compared with PET/CT. Previous scanning experiences and patients' interactions prior to and during PET/MRI improved patient satisfaction. Interventions could be implemented to improve imaging outcome. Advances in knowledge: This study provides evidence for the increased psychological burden of PET/MRI compared with PET/CT, and that people prefer the PET/CT procedure. We have shown that the patients who expressed a preference for PET/MRI demonstrated significantly lower psychological burden for that procedure than those that preferred PET/CT, which indicates that the benefit of reduced

  20. Image reconstruction for 3D light microscopy with a regularized linear method incorporating a smoothness prior

    NASA Astrophysics Data System (ADS)

    Preza, Chrysanthe; Miller, Michael I.; Conchello, Jose-Angel

    1993-07-01

    We have shown that the linear least-squares (LLS) estimate of the intensities of a 3-D object obtained from a set of optical sections is unstable due to the inversion of small and zero-valued eigenvalues of the point-spread function (PSF) operator. The LLS solution was regularized by constraining it to lie in a subspace spanned by the eigenvectors corresponding to a selected number of the largest eigenvalues. In this paper we extend the regularized LLS solution to a maximum a posteriori (MAP) solution induced by a prior formed from a 'Good's like' smoothness penalty. This approach also yields a regularized linear estimator which reduces noise as well as edge artifacts in the reconstruction. The advantage of the linear MAP (LMAP) estimate over the current regularized LLS (RLLS) is its ability to regularize the inverse problem by smoothly penalizing components in the image associated with small eigenvalues. Computer simulations were performed using a theoretical PSF and a simple phantom to compare the two regularization techniques. It is shown that the reconstructions using the smoothness prior, give superior variance and bias results compared to the RLLS reconstructions. Encouraging reconstructions obtained with the LMAP method from real microscopical images of a 10 micrometers fluorescent bead, and a four-cell Volvox embryo are shown.

  1. The effects of prior pain experience on neural correlates of empathy for pain: An fMRI study.

    PubMed

    Preis, Mira A; Schmidt-Samoa, Carsten; Dechent, Peter; Kroener-Herwig, Birgit

    2013-03-01

    Neuroimaging studies have revealed partially shared neural substrates for both the actual experience of pain and empathy elicited by the pain of others. We examined whether prior pain exposure increased neural activity in the anterior midcingulate cortex (aMCC) and bilateral anterior insula (AI) as a correlate of empathy for pain. Participants (N=64: 32 women, 32 men) viewed pictures displaying exposure to pressure pain (pain pictures) and pictures without any cue of pain (neutral pictures). Prior to the experiment, half of the participants were exposed to the same pain stimulus as the one seen in the pain pictures (pain exposure condition); the other half had no such experience (touch exposure condition). A balanced sex ratio was kept, to investigate possible sex differences. In the region-of-interest analyses, participants of the pain exposure condition showed decreased activity in the right AI and the aMCC relative to participants of the touch exposure condition. While in men, no differences were found in relation to their exposure condition, women with pain exposure showed decreased activity in the aMCC and additionally, in bilateral AI. Based on the entire sample, whole brain analyses revealed stronger activation in the retrosplenial cortex, dorsomedial prefrontal cortex, and medial prefrontal cortex in the pain exposure condition. In conclusion, prior pain exposure did not increase, but decreased activity in regions regularly associated with empathy for pain. However, pain experience increased activity in regions associated with memory retrieval, perspective taking, and top-down emotion regulation, which might facilitate empathizing with others.

  2. Reconstruction of 7T-Like Images From 3T MRI.

    PubMed

    Bahrami, Khosro; Shi, Feng; Zong, Xiaopeng; Shin, Hae Won; An, Hongyu; Shen, Dinggang

    2016-09-01

    In the recent MRI scanning, ultra-high-field (7T) MR imaging provides higher resolution and better tissue contrast compared to routine 3T MRI, which may help in more accurate and early brain diseases diagnosis. However, currently, 7T MRI scanners are more expensive and less available at clinical and research centers. These motivate us to propose a method for the reconstruction of images close to the quality of 7T MRI, called 7T-like images, from 3T MRI, to improve the quality in terms of resolution and contrast. By doing so, the post-processing tasks, such as tissue segmentation, can be done more accurately and brain tissues details can be seen with higher resolution and contrast. To do this, we have acquired a unique dataset which includes paired 3T and 7T images scanned from same subjects, and then propose a hierarchical reconstruction based on group sparsity in a novel multi-level Canonical Correlation Analysis (CCA) space, to improve the quality of 3T MR image to be 7T-like MRI. First, overlapping patches are extracted from the input 3T MR image. Then, by extracting the most similar patches from all the aligned 3T and 7T images in the training set, the paired 3T and 7T dictionaries are constructed for each patch. It is worth noting that, for the training, we use pairs of 3T and 7T MR images from each training subject. Then, we propose multi-level CCA to map the paired 3T and 7T patch sets to a common space to increase their correlations. In such space, each input 3T MRI patch is sparsely represented by the 3T dictionary and then the obtained sparse coefficients are used together with the corresponding 7T dictionary to reconstruct the 7T-like patch. Also, to have the structural consistency between adjacent patches, the group sparsity is employed. This reconstruction is performed with changing patch sizes in a hierarchical framework. Experiments have been done using 13 subjects with both 3T and 7T MR images. The results show that our method outperforms previous

  3. Reconstruction of 7T-Like Images From 3T MRI.

    PubMed

    Bahrami, Khosro; Shi, Feng; Zong, Xiaopeng; Shin, Hae Won; An, Hongyu; Shen, Dinggang

    2016-09-01

    In the recent MRI scanning, ultra-high-field (7T) MR imaging provides higher resolution and better tissue contrast compared to routine 3T MRI, which may help in more accurate and early brain diseases diagnosis. However, currently, 7T MRI scanners are more expensive and less available at clinical and research centers. These motivate us to propose a method for the reconstruction of images close to the quality of 7T MRI, called 7T-like images, from 3T MRI, to improve the quality in terms of resolution and contrast. By doing so, the post-processing tasks, such as tissue segmentation, can be done more accurately and brain tissues details can be seen with higher resolution and contrast. To do this, we have acquired a unique dataset which includes paired 3T and 7T images scanned from same subjects, and then propose a hierarchical reconstruction based on group sparsity in a novel multi-level Canonical Correlation Analysis (CCA) space, to improve the quality of 3T MR image to be 7T-like MRI. First, overlapping patches are extracted from the input 3T MR image. Then, by extracting the most similar patches from all the aligned 3T and 7T images in the training set, the paired 3T and 7T dictionaries are constructed for each patch. It is worth noting that, for the training, we use pairs of 3T and 7T MR images from each training subject. Then, we propose multi-level CCA to map the paired 3T and 7T patch sets to a common space to increase their correlations. In such space, each input 3T MRI patch is sparsely represented by the 3T dictionary and then the obtained sparse coefficients are used together with the corresponding 7T dictionary to reconstruct the 7T-like patch. Also, to have the structural consistency between adjacent patches, the group sparsity is employed. This reconstruction is performed with changing patch sizes in a hierarchical framework. Experiments have been done using 13 subjects with both 3T and 7T MR images. The results show that our method outperforms previous

  4. Strain Rate Tensor Estimation in Cine Cardiac MRI Based on Elastic Image Registration

    NASA Astrophysics Data System (ADS)

    Sánchez-Ferrero, Gonzalo Vegas; Vega, Antonio Tristán; Grande, Lucilio Cordero; de La Higuera, Pablo Casaseca; Fernández, Santiago Aja; Fernández, Marcos Martín; López, Carlos Alberola

    In this work we propose an alternative method to estimate and visualize the Strain Rate Tensor (SRT) in Magnetic Resonance Images (MRI) when Phase Contrast MRI (PCMRI) and Tagged MRI (TMRI) are not available. This alternative is based on image processing techniques. Concretely, image registration algorithms are used to estimate the movement of the myocardium at each point. Additionally, a consistency checking method is presented to validate the accuracy of the estimates when no golden standard is available. Results prove that the consistency checking method provides an upper bound of the mean squared error of the estimate. Our experiments with real data show that the registration algorithm provides a useful deformation field to estimate the SRT fields. A classification between regional normal and dysfunctional contraction patterns, as compared with experts diagnosis, points out that the parameters extracted from the estimated SRT can represent these patterns. Additionally, a scheme for visualizing and analyzing the local behavior of the SRT field is presented.

  5. Identification and description of the axillary web syndrome (AWS) by clinical signs, MRI and US imaging.

    PubMed

    Leduc, O; Fumière, E; Banse, S; Vandervorst, C; Clément, A; Parijs, T; Wilputte, F; Maquerlot, F; Ezquer Echandia, M; Tinlot, A; Leduc, A

    2014-12-01

    The Axillary Web Syndrome (AWS) follows surgery for breast neoplasia and consists of one, or more frequently two or three, cords of subcutaneous tissue. Cords originate from the axilla, spread to the antero-medial surface of the arm down to the elbow and then move into the antero-medial aspect of the forearm and sometimes into the root of the thumb. The purpose of this study was to compare two techniques, ultrasound (US) and Magnetic Resonance Imaging (MRI) for their sensitivity and accuracy in identifying AWS cords and to provide insights to the origin of this pathology. US examinations were performed on fifteen patients using a high frequency probe (17 MHz). We first palpated and marked the cord with location aided by maximum abduction. To identify the cord with MRI (1.5 Tesla), a catheter filled with a gel detectable under MRI was placed on the skin at the site of the cord. We found that in some US cases, the dynamic abduction maneuver was essential to facilitate detection of the cord. This dynamic method on ultrasound confirmed the precise location of the cord even if it was located deeper in the hypodermis fascia junction. US and MRI images revealed features of the cords and surrounding tissues. Imaging the cords was difficult with either of the imaging modalities. However, US seemed to be more efficient than MRI and allowed dynamic evaluation. Overall analysis of our study results supports a lymphatic origin of the AWS cord.

  6. Identification and description of the axillary web syndrome (AWS) by clinical signs, MRI and US imaging.

    PubMed

    Leduc, O; Fumière, E; Banse, S; Vandervorst, C; Clément, A; Parijs, T; Wilputte, F; Maquerlot, F; Ezquer Echandia, M; Tinlot, A; Leduc, A

    2014-12-01

    The Axillary Web Syndrome (AWS) follows surgery for breast neoplasia and consists of one, or more frequently two or three, cords of subcutaneous tissue. Cords originate from the axilla, spread to the antero-medial surface of the arm down to the elbow and then move into the antero-medial aspect of the forearm and sometimes into the root of the thumb. The purpose of this study was to compare two techniques, ultrasound (US) and Magnetic Resonance Imaging (MRI) for their sensitivity and accuracy in identifying AWS cords and to provide insights to the origin of this pathology. US examinations were performed on fifteen patients using a high frequency probe (17 MHz). We first palpated and marked the cord with location aided by maximum abduction. To identify the cord with MRI (1.5 Tesla), a catheter filled with a gel detectable under MRI was placed on the skin at the site of the cord. We found that in some US cases, the dynamic abduction maneuver was essential to facilitate detection of the cord. This dynamic method on ultrasound confirmed the precise location of the cord even if it was located deeper in the hypodermis fascia junction. US and MRI images revealed features of the cords and surrounding tissues. Imaging the cords was difficult with either of the imaging modalities. However, US seemed to be more efficient than MRI and allowed dynamic evaluation. Overall analysis of our study results supports a lymphatic origin of the AWS cord. PMID:25915977

  7. Multimodal imaging with hybrid semiconductor detectors Timepix for an experimental MRI-SPECT system

    NASA Astrophysics Data System (ADS)

    Zajicek, J.; Jakubek, J.; Burian, M.; Vobecky, M.; Fauler, A.; Fiederle, M.; Zwerger, A.

    2013-01-01

    An increasing number of clinical applications are being based on multimodal imaging systems (MIS), including anatomical (CT, MRI) and functional (PET, SPECT) techniques to provide complex information in a single image. CT with one of the scintigraphic methods (PET or SPECT) is nowadays a combination of choice for clinical practice and it is mostly used in cardiography and tumour diagnostics. Combination with MRI is also being implemented as no radiation dose is imparted to the patient and it is possible to gain higher structural resolution of soft tissues (brain imaging). A major disadvantage of such systems is inability to operate scintillators with photomultipliers (used for detection of γ rays) in presence of high magnetic fields. In this work we present the application of the semiconductor pixel detector for SPECT method in combination with MR imaging. We propose a novel approach based on MRI compatible setup with CdTe pixel sensor Timepix and non-conductive collimator. Measurements were performed on high proton-density (PD) phantom (1H) with an embedded radioisotopic source inside the shielded RF coil by MRI animal scanner (4.7 T). Our results pave the way for a combined MRI-SPECT system. The project was performed in the framework of the Medipix Collaboration.

  8. Evaluation of image quality of MRI data for brain tumor surgery

    NASA Astrophysics Data System (ADS)

    Heckel, Frank; Arlt, Felix; Geisler, Benjamin; Zidowitz, Stephan; Neumuth, Thomas

    2016-03-01

    3D medical images are important components of modern medicine. Their usefulness for the physician depends on their quality, though. Only high-quality images allow accurate and reproducible diagnosis and appropriate support during treatment. We have analyzed 202 MRI images for brain tumor surgery in a retrospective study. Both an experienced neurosurgeon and an experienced neuroradiologist rated each available image with respect to its role in the clinical workflow, its suitability for this specific role, various image quality characteristics, and imaging artifacts. Our results show that MRI data acquired for brain tumor surgery does not always fulfill the required quality standards and that there is a significant disagreement between the surgeon and the radiologist, with the surgeon being more critical. Noise, resolution, as well as the coverage of anatomical structures were the most important criteria for the surgeon, while the radiologist was mainly disturbed by motion artifacts.

  9. 99mTechnetium HMPAO imaging in children with the Sturge-Weber syndrome: a study of nine cases with CT and MRI correlation.

    PubMed

    Griffiths, P D; Boodram, M B; Blaser, S; Armstrong, D; Gilday, D L; Harwood-Nash, D

    1997-03-01

    Demonstration of the full extent of abnormality in patients with the Struge-Weber syndrome (SWS) is important for prognosis and in planning surgery to remove the seizure focus. We compared single-photon emission computed tomography (SPECT), MRI and CT in nine children under the age of 4 years with seizures as part of SWS, in an attempt to determine the optimal method of imaging in different clinical settings. Seven unilateral and two bilateral cases were studied by interictal 99mtechnetium hexamethylpropyleneamineoxime (HMPAO) SPECT, and contrast-enhanced CT and MRI, giving information on 11 abnormal hemispheres. All imaging modalities showed abnormalities in every child. Perfusion imaging showed focal regions of decreased uptake in 9 of 11 (82%) abnormal hemispheres and demonstrated a widespread decrease but no focal defect in 2; it also revealed crossed cerebellar diaschisis in 2 cases. CT demonstrated typical gyriform calcification in 9 of 11 (82%) affected hemispheres. Contrast-enhanced MRI showed more extensive involvement than contrast-enhanced CT in 5 of 11 (45%) cases. The area of hypoperfusion shown by SPECT was smaller than the area of contrast enhancement on MRI in 6 of 11 cases (55%), comparable in 3 (27%) and larger in 2 cases (18%). CT is sufficient to confirm the clinical diagnosis of SWS, but MRI frequently shows more extensive abnormal areas. 99mTc HMPAO imaging is a useful addition when it is important to know the full extent of the disease, for example prior to surgery. It is likely to detect areas of hypoperfusion, representing ischaemic regions, which may act as an epileptogenic focus and may not be shown by CT or MRI.

  10. Visualising uncertainty: Examining women's views on the role of Magnetic Resonance Imaging (MRI) in late pregnancy.

    PubMed

    Reed, Kate; Kochetkova, Inna; Whitby, Elspeth

    2016-09-01

    Prenatal screening occupies a prominent role within sociological debates on medical uncertainty. A particular issue concerns the limitations of routine screening which tends to be based on risk prediction. Computer assisted visual technologies such as Magnetic Resonance Imaging (MRI) are now starting to be applied to the prenatal realm to assist in the diagnosis of a range of fetal and maternal disorders (from problems with the fetal brain to the placenta). MRI is often perceived in popular and medical discourse as a technology of certainty and truth. However, little is known about the use of MRI as a tool to confirm or refute the diagnosis of a range of disorders in pregnancy. Drawing on qualitative research with pregnant women attending a fetal medicine clinic in the North of England this paper examines the potential role that MRI can play in mediating pregnancy uncertainty. The paper will argue that MRI can create and manage women's feelings of uncertainty during pregnancy. However, while MRI may not always provide women with unequivocal answers, the detailed information provided by MR images combined with the interpretation and communication skills of the radiologist in many ways enables women to navigate the issue. Our analysis of empirical data therefore highlights the value of this novel technological application for women and their partners. It also seeks to stress the merit of taking a productive approach to the study of diagnostic uncertainty, an approach which recognises the concepts dual nature. PMID:27451338

  11. Visualising uncertainty: Examining women's views on the role of Magnetic Resonance Imaging (MRI) in late pregnancy.

    PubMed

    Reed, Kate; Kochetkova, Inna; Whitby, Elspeth

    2016-09-01

    Prenatal screening occupies a prominent role within sociological debates on medical uncertainty. A particular issue concerns the limitations of routine screening which tends to be based on risk prediction. Computer assisted visual technologies such as Magnetic Resonance Imaging (MRI) are now starting to be applied to the prenatal realm to assist in the diagnosis of a range of fetal and maternal disorders (from problems with the fetal brain to the placenta). MRI is often perceived in popular and medical discourse as a technology of certainty and truth. However, little is known about the use of MRI as a tool to confirm or refute the diagnosis of a range of disorders in pregnancy. Drawing on qualitative research with pregnant women attending a fetal medicine clinic in the North of England this paper examines the potential role that MRI can play in mediating pregnancy uncertainty. The paper will argue that MRI can create and manage women's feelings of uncertainty during pregnancy. However, while MRI may not always provide women with unequivocal answers, the detailed information provided by MR images combined with the interpretation and communication skills of the radiologist in many ways enables women to navigate the issue. Our analysis of empirical data therefore highlights the value of this novel technological application for women and their partners. It also seeks to stress the merit of taking a productive approach to the study of diagnostic uncertainty, an approach which recognises the concepts dual nature.

  12. MRI reporter genes: applications for imaging of cell survival, proliferation, migration and differentiation.

    PubMed

    Vandsburger, Moriel H; Radoul, Marina; Cohen, Batya; Neeman, Michal

    2013-07-01

    Molecular imaging strives to detect molecular events at the level of the whole organism. In some cases, the molecule of interest can be detected either directly or with targeted contrast media. However many genes and proteins and particularly those located in intracellular compartments are not accessible for targeted agents. The transcriptional regulation of these genes can nevertheless be detected, although indirectly, using reporter gene encoding for readily detectable proteins. Such reporter proteins can be expressed in the tissue of interest by genetically introducing the reporter gene in the target cells. Imaging of reporter genes has become a powerful tool in modern biomedical research. Typically, expression of fluorescent and bioluminescent proteins and the reaction product of expressed enzymes and exogenous substrates were examined using in vitro histological methods and in vivo whole body imaging methods. Recent advances in MRI reporter gene methods raised the possibility that MRI could become a powerful tool for concomitant high-resolution anatomical and functional imaging and for imaging of reporter gene activity. An immediate application of MRI reporter gene methods was by monitoring gene expression patterns in gene therapy and in vivo imaging of the survival, proliferation, migration and differentiation of pluripotent and multipotent cells used in cell-based regenerative therapies for cancer, myocardial infarction and neural degeneration. In this review, we characterized a variety of MRI reporter gene methods based on their applicability to report cell survival/proliferation, migration and differentiation. In particular, we discussed which methods were best suited for translation to clinical use in regenerative therapies.

  13. Carotid plaque characterization using CT and MRI scans for synergistic image analysis

    NASA Astrophysics Data System (ADS)

    Getzin, Matthew; Xu, Yiqin; Rao, Arhant; Madi, Saaussan; Bahadur, Ali; Lennartz, Michelle R.; Wang, Ge

    2014-09-01

    Noninvasive determination of plaque vulnerability has been a holy grail of medical imaging. Despite advances in tomographic technologies , there is currently no effective way to identify vulnerable atherosclerotic plaques with high sensitivity and specificity. Computed tomography (CT) and magnetic resonance imaging (MRI) are widely used, but neither provides sufficient information of plaque properties. Thus, we are motivated to combine CT and MRI imaging to determine if the composite information can better reflect the histological determination of plaque vulnerability. Two human endarterectomy specimens (1 symptomatic carotid and 1 stable femoral) were imaged using Scanco Medical Viva CT40 and Bruker Pharmascan 16cm 7T Horizontal MRI / MRS systems. μCT scans were done at 55 kVp and tube current of 70 mA. Samples underwent RARE-VTR and MSME pulse sequences to measure T1, T2 values, and proton density. The specimens were processed for histology and scored for vulnerability using the American Heart Association criteria. Single modality-based analyses were performed through segmentation of key imaging biomarkers (i.e. calcification and lumen), image registration, measurement of fibrous capsule, and multi-component T1 and T2 decay modeling. Feature differences were analyzed between the unstable and stable controls, symptomatic carotid and femoral plaque, respectively. By building on the techniques used in this study, synergistic CT+MRI analysis may provide a promising solution for plaque characterization in vivo.

  14. Magnetic resonance imaging (MRI) in the diagnosis of head and neck disease.

    PubMed

    Supsupin, Emilio P; Demian, Nagi M

    2014-05-01

    Magnetic resonance imaging (MRI) is the modality of choice to identify intracranial or perineural spread from a head and neck primary tumor. Perineural spread is a form of metastatic disease in which primary tumors spread along neural pathways. Orbital cellulitis is a sight-threatening, and potentially life-threatening condition. Urgent imaging is performed to assess the anatomic extent of disease, including postseptal, cavernous sinus, and intracranial involvement, and identify orbital abscesses that require exploration and drainage. MRI is useful in the evaluation of the brachial plexus.

  15. Magnetic resonance imaging (MRI) in the diagnosis of head and neck disease.

    PubMed

    Supsupin, Emilio P; Demian, Nagi M

    2014-05-01

    Magnetic resonance imaging (MRI) is the modality of choice to identify intracranial or perineural spread from a head and neck primary tumor. Perineural spread is a form of metastatic disease in which primary tumors spread along neural pathways. Orbital cellulitis is a sight-threatening, and potentially life-threatening condition. Urgent imaging is performed to assess the anatomic extent of disease, including postseptal, cavernous sinus, and intracranial involvement, and identify orbital abscesses that require exploration and drainage. MRI is useful in the evaluation of the brachial plexus. PMID:24794270

  16. Crossed cerebral lateralization for verbal and visuo-spatial function in a pair of handedness discordant monozygotic twins: MRI and fMRI brain imaging

    PubMed Central

    Lux, Silke; Keller, Simon; Mackay, Clare; Ebers, George; Marshall, John C; Cherkas, Lynne; Rezaie, Roozbeh; Roberts, Neil; Fink, Gereon R; Gurd, Jennifer M

    2008-01-01

    To examine the nature of hemispheric lateralization for neural processes underlying verbal fluency and visuo-spatial attention, we investigated a single pair of handedness discordant monozygotic (MzHd) twins. Imaging of the brain was undertaken using magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) in combination with manual performance tasks. The twins were discordant for MRI anatomical asymmetries of the pars triangularis and planum temporale, whose asymmetry was consistent with verbal laterality on fMRI. Thus, the right-handed twin had left lateralized verbal with right lateralized visuo-spatial attention, while the left-handed twin had right lateralized verbal with left lateralized visuo-spatial activation; these data lend further support for to the conclusions of Sommer et al. PMID:18304205

  17. MRI Scans

    MedlinePlus

    Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body. Health care professionals use MRI scans to diagnose a variety of conditions, from torn ...

  18. The value of magnetic resonance imaging and ultrasonography (MRI/US)-fusion biopsy platforms in prostate cancer detection: a systematic review.

    PubMed

    Gayet, Maudy; van der Aa, Anouk; Beerlage, Harrie P; Schrier, Bart Ph; Mulders, Peter F A; Wijkstra, Hessel

    2016-03-01

    Despite limitations considering the presence, staging and aggressiveness of prostate cancer, ultrasonography (US)-guided systematic biopsies (SBs) are still the 'gold standard' for the diagnosis of prostate cancer. Recently, promising results have been published for targeted prostate biopsies (TBs) using magnetic resonance imaging (MRI) and ultrasonography (MRI/US)-fusion platforms. Different platforms are USA Food and Drug Administration registered and have, mostly subjective, strengths and weaknesses. To our knowledge, no systematic review exists that objectively compares prostate cancer detection rates between the different platforms available. To assess the value of the different MRI/US-fusion platforms in prostate cancer detection, we compared platform-guided TB with SB, and other ways of MRI TB (cognitive fusion or in-bore MR fusion). We performed a systematic review of well-designed prospective randomised and non-randomised trials in the English language published between 1 January 2004 and 17 February 2015, using PubMed, Embase and Cochrane Library databases. Search terms included: 'prostate cancer', 'MR/ultrasound(US) fusion' and 'targeted biopsies'. Extraction of articles was performed by two authors (M.G. and A.A.) and were evaluated by the other authors. Randomised and non-randomised prospective clinical trials comparing TB using MRI/US-fusion platforms and SB, or other ways of TB (cognitive fusion or MR in-bore fusion) were included. In all, 11 of 1865 studies met the inclusion criteria, involving seven different fusion platforms and 2626 patients: 1119 biopsy naïve, 1433 with prior negative biopsy, 50 not mentioned (either biopsy naïve or with prior negative biopsy) and 24 on active surveillance (who were disregarded). The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used to assess the quality of included articles. No clear advantage of MRI/US fusion-guided TBs was seen for cancer detection rates (CDRs) of all prostate

  19. Image Denoising via Bayesian Estimation of Statistical Parameter Using Generalized Gamma Density Prior in Gaussian Noise Model

    NASA Astrophysics Data System (ADS)

    Kittisuwan, Pichid

    2015-03-01

    The application of image processing in industry has shown remarkable success over the last decade, for example, in security and telecommunication systems. The denoising of natural image corrupted by Gaussian noise is a classical problem in image processing. So, image denoising is an indispensable step during image processing. This paper is concerned with dual-tree complex wavelet-based image denoising using Bayesian techniques. One of the cruxes of the Bayesian image denoising algorithms is to estimate the statistical parameter of the image. Here, we employ maximum a posteriori (MAP) estimation to calculate local observed variance with generalized Gamma density prior for local observed variance and Laplacian or Gaussian distribution for noisy wavelet coefficients. Evidently, our selection of prior distribution is motivated by efficient and flexible properties of generalized Gamma density. The experimental results show that the proposed method yields good denoising results.

  20. Magnetic resonance imaging (MRI) detection of the murine brain response to light: Temporal differentiation and negative functional MRI changes

    SciTech Connect

    Huang, Wei ||; Palyka, I. |; Li, HaiFang

    1996-06-11

    Using a 9.4 T MRI instrument, we have obtained images of the mouse brain response to photic stimulation during a period between deep anesthesia and the early stages of arousal. The large image enhancements we observe (often >30%) are consistent with literature results extrapolated to 9.4 T. However, there are also two unusual aspects to our findings. (i) The visual area of the brain responds only to changes in stimulus intensity, suggesting that we directly detect operations of the M visual system pathway. Such a channel has been observed in mice by invasive electrophysiology, and described in detail for primates. (ii) Along with the typical positive response in the area of the occipital portion of the brain containing the visual cortex; another area displays decreased signal intensity upon stimulation. 41 refs., 4 figs.

  1. The Movement of a Nerve in a Magnetic Field: Application to MRI Lorentz Effect Imaging

    PubMed Central

    Roth, Bradley J.; Luterek, Adam; Puwal, Steffan

    2014-01-01

    Direct detection of neural activity with MRI would be a breakthrough innovation in brain imaging. A Lorentz force method has been proposed to image nerve activity using MRI; a force between the action currents and the static MRI magnetic field causes the nerve to move. In the presence of a magnetic field gradient, this will cause the spins to precess at a different frequency, affecting the MRI signal. Previous mathematical modeling suggests that this effect is too small to explain the experimental data, but that model was limited because the action currents were assumed to be independent of position along the nerve, and because the magnetic field was assumed to be perpendicular to the nerve. In this paper, we calculate the nerve displacement analytically without these two assumptions. Using realistic parameter values, the nerve motion is less than 5 nm, which induced a phase shift in the MRI signal of less than 0.02°. Therefore, our results suggest that Lorentz force imaging is beyond the capabilities of current technology. PMID:24728667

  2. Imaging artifacts induced by electrical stimulation during conventional fMRI of the brain

    PubMed Central

    Antal, Andrea; Bikson, Marom; Datta, Abhishek; Lafon, Belen; Dechent, Peter; Parra, Lucas C.; Paulus, Walter

    2013-01-01

    Functional magnetic resonance imaging (fMRI) of brain activation during transcranial electrical stimulation is used to provide insight into the mechanisms of neuromodulation and targeting of particular brain structures. However, the passage of current through the body may interfere with the concurrent detection of blood oxygen level dependent (BOLD) signal, which is sensitive to local magnetic fields. To test whether these currents can affect concurrent fMRI recordings we performed conventional gradient echo-planar imaging (EPI) during transcranial direct current (tDCS) and alternating current stimulation (tACS) on two post-mortem subjects. TDCS induced signals in both superficial and deep structures. The signal was specific to the electrode montage, with the strongest signal near cerebrospinal fluid (CSF) and scalp. The direction of change relative to non-stimulation reversed with tDCS stimulation polarity. For tACS there was no net effect of the MRI signal. High-resolution individualized modeling of current flow and induced static magnetic fields suggested a strong coincidence of the change EPI signal with regions of large current density and magnetic fields. These initial results indicate that: 1) fMRI studies of tDCS must consider this potentially confounding interference from current flow and 2) conventional MRI imaging protocols can be potentially used to measure current flow during transcranial electrical stimulation. The optimization of current measurement and artifact correction techniques, including consideration of the underlying physics, remains to be addressed. PMID:23099102

  3. In Vivo Imaging of Stepwise Vessel Occlusion in Cerebral Photothrombosis of Mice by 19F MRI

    PubMed Central

    Kleinschnitz, Christoph; Kampf, Thomas; Jakob, Peter M.; Stoll, Guido

    2011-01-01

    Background 19F magnetic resonance imaging (MRI) was recently introduced as a promising technique for in vivo cell tracking. In the present study we compared 19F MRI with iron-enhanced MRI in mice with photothrombosis (PT) at 7 Tesla. PT represents a model of focal cerebral ischemia exhibiting acute vessel occlusion and delayed neuroinflammation. Methods/Principal Findings Perfluorocarbons (PFC) or superparamagnetic iron oxide particles (SPIO) were injected intravenously at different time points after photothrombotic infarction. While administration of PFC directly after PT induction led to a strong 19F signal throughout the entire lesion, two hours delayed application resulted in a rim-like 19F signal at the outer edge of the lesion. These findings closely resembled the distribution of signal loss on T2-weighted MRI seen after SPIO injection reflecting intravascular accumulation of iron particles trapped in vessel thrombi as confirmed histologically. By sequential administration of two chemically shifted PFC compounds 0 and 2 hours after illumination the different spatial distribution of the 19F markers (infarct core/rim) could be visualized in the same animal. When PFC were applied at day 6 the fluorine marker was only detected after long acquisition times ex vivo. SPIO-enhanced MRI showed slight signal loss in vivo which was much more prominent ex vivo indicative for neuroinflammation at this late lesion stage. Conclusion Our study shows that vessel occlusion can be followed in vivo by 19F and SPIO-enhanced high-field MRI while in vivo imaging of neuroinflammation remains challenging. The timing of contrast agent application was the major determinant of the underlying processes depicted by both imaging techniques. Importantly, sequential application of different PFC compounds allowed depiction of ongoing vessel occlusion from the core to the margin of the ischemic lesions in a single MRI measurement. PMID:22194810

  4. A high accuracy multi-image registration method for tracking MRI-guided robots

    NASA Astrophysics Data System (ADS)

    Shang, Weijian; Fischer, Gregory S.

    2012-02-01

    Recent studies have demonstrated an increasing number of functional surgical robots and other devices operating in the Magnetic Resonance Imaging (MRI) environment. Calibration and tracking of the robotic device is essential during such MRI-guided procedures. A fiducial tracking module is placed on the base or the end effector of the robot to localize it within the scanner, and thus the patient coordinate system. The fiducial frame represents a Z shape and is made of seven tubes filled with high contrast fluid. The frame is highlighted in the MR images and is used in localization. Compared to the former single image registration method, multiple images are used in this algorithm to calculate the position and orientation of the frame, and thus the robot. By using multiple images together, measurement error is reduced and the rigid requirement of slow to acquire high quality of images is not required. Accuracy and performance were evaluated in experiments which were operated with a Philips 3T MRI scanner. Presented is an accuracy comparison of the new method with varied number of images, and a comparison to more traditional single image registration techniques.

  5. Measurement of Strain in the Left Ventricle during Diastole withcine-MRI and Deformable Image Registration

    SciTech Connect

    Veress, Alexander I.; Gullberg, Grant T.; Weiss, Jeffrey A.

    2005-07-20

    The assessment of regional heart wall motion (local strain) can localize ischemic myocardial disease, evaluate myocardial viability and identify impaired cardiac function due to hypertrophic or dilated cardiomyopathies. The objectives of this research were to develop and validate a technique known as Hyperelastic Warping for the measurement of local strains in the left ventricle from clinical cine-MRI image datasets. The technique uses differences in image intensities between template (reference) and target (loaded) image datasets to generate a body force that deforms a finite element (FE) representation of the template so that it registers with the target image. To validate the technique, MRI image datasets representing two deformation states of a left ventricle were created such that the deformation map between the states represented in the images was known. A beginning diastoliccine-MRI image dataset from a normal human subject was defined as the template. A second image dataset (target) was created by mapping the template image using the deformation results obtained from a forward FE model of diastolic filling. Fiber stretch and strain predictions from Hyperelastic Warping showed good agreement with those of the forward solution. The technique had low sensitivity to changes in material parameters, with the exception of changes in bulk modulus of the material. The use of an isotropic hyperelastic constitutive model in the Warping analyses degraded the predictions of fiber stretch. Results were unaffected by simulated noise down to an SNR of 4.0. This study demonstrates that Warping in conjunction with cine-MRI imaging can be used to determine local ventricular strains during diastole.

  6. Imaging techniques: MRI illuminated by γ-rays

    NASA Astrophysics Data System (ADS)

    Bowtell, Richard

    2016-09-01

    A technique that combines magnetic resonance with nuclear medicine has been used to image the distribution of a radioactive tracer, potentially opening up a powerful and innovative approach to medical imaging. See Letter p.652

  7. Segmentation of densely populated cell nuclei from confocal image stacks using 3D non-parametric shape priors.

    PubMed

    Ong, Lee-Ling S; Wang, Mengmeng; Dauwels, Justin; Asada, H Harry

    2014-01-01

    An approach to jointly estimate 3D shapes and poses of stained nuclei from confocal microscopy images, using statistical prior information, is presented. Extracting nuclei boundaries from our experimental images of cell migration is challenging due to clustered nuclei and variations in their shapes. This issue is formulated as a maximum a posteriori estimation problem. By incorporating statistical prior models of 3D nuclei shapes into level set functions, the active contour evolutions applied on the images is constrained. A 3D alignment algorithm is developed to build the training databases and to match contours obtained from the images to them. To address the issue of aligning the model over multiple clustered nuclei, a watershed-like technique is used to detect and separate clustered regions prior to active contour evolution. Our method is tested on confocal images of endothelial cells in microfluidic devices, compared with existing approaches.

  8. Imaging of tarsal navicular stress injury with a focus on MRI: A pictorial essay.

    PubMed

    Harris, Guy; Harris, Craig

    2016-06-01

    Predominantly diagnosed in athletes, stress fracture of the tarsal navicular is becoming increasingly recognised by clinicians as a cause of midfoot pain. Delayed diagnosis can increase the significant morbidity associated with this condition. Consequently the role of MRI is increasing, given the potential to identify a stress reaction in the navicular prior to the development of a discrete stress fracture. It is necessary for radiologists to be familiar with the typical and atypical appearances of this important condition.

  9. Imaging of adult flatfoot: correlation of radiographic measurements with MRI.

    PubMed

    Lin, Yu-Ching; Mhuircheartaigh, Jennifer Ni; Lamb, Joshua; Kung, Justin W; Yablon, Corrie M; Wu, Jim S

    2015-02-01

    OBJECTIVE. The purpose of this study is to determine whether radiographic foot measurements can predict injury of the posterior tibial tendon (PTT) and the supporting structures of the medial longitudinal arch as diagnosed on MRI. MATERIALS AND METHODS. After institutional review board approval, 100 consecutive patients with radiographic and MRI examinations performed within a 2-month period were enrolled. Thirty-one patients had PTT dysfunction clinically, and 69 patients had other causes of ankle pain. Talonavicular uncoverage angle, incongruency angle, calcaneal pitch angle, Meary angle, cuneiform-to-fifth metatarsal height, and talar tilt were calculated on standing foot or ankle radiographs. MRI was used to assess for abnormalities of the PTT (tenosynovitis, tendinosis, and tear) and supporting structures of the medial longitudinal arch (spring ligament, deltoid ligament, and sinus tarsi). Statistical analysis was performed using the chi-square and Fisher exact tests for categoric variables; the Student t test was used for continuous variables. RESULTS. There was a statistically significant association of PTT tear with abnormal talonavicular uncoverage angle, calcaneal pitch angle, Meary angle, and cuneiform-to-fifth metatarsal height. PTT tendinosis and isolated tenosynovitis had a poor association with most radiologic measurements. If both calcaneal pitch and Meary angles were normal, no PTT tear was present. An abnormal calcaneal pitch angle had the best association with injury to the supporting medial longitudinal arch structures. CONCLUSION. Radiographic measurements, especially calcaneal pitch and Meary angles, can be useful in detecting PTT tears. Calcaneal pitch angle provides the best assessment of injury to the supporting structures of the medial longitudinal arch.

  10. Image Registration for Quantitative Analysis of Kidney Function using MRI

    NASA Astrophysics Data System (ADS)

    Sance, Rosario; Ledesma-Carbayo, María J.; Lundervold, Arvid; Santos, Andrés

    2006-10-01

    The aim of the present study is to analyze the possibilities of registration algorithms to compensate respiratory motion and deformation in abdominal DCE-MRI 3D temporary series. The final objective is that from registered data, appropriate intensity curves of local renal activity along the time could be represented for each kidney voxel. Assuming a relation between the voxel intensity and the contrast media concentration, this non-invasive renographic method could be used to evaluate the local renal function, and to calculate typical renal parameters like glomerular filtration rate.

  11. Philips 3T Intera Magnetic Resonance Imaging System and Upgrade of existing MRI equipment

    SciTech Connect

    Evanochko, William T

    2004-05-14

    The objective of this proposal was twofold. First, upgrade existing MRI equipment, specifically a research 4.1T whole-body system. Second, purchase a clinical, state-of-the-art 3T MRI system tailored specifically to cardiovascular and neurological applications. This project was within the guidelines of ''Medical Applications and Measurement Science''. The goals were: [1] to develop beneficial applications of magnetic resonance imaging; [2] discover new applications of MR strategies for medical research; and [2] apply them for clinical diagnosis. Much of this proposal searched for breakthroughs in this noninvasive and nondestructive imaging technology. Finally, this proposal's activities focused on research in the basic science of chemistry, biochemistry, physics, and engineering as applied to bioengineering. The centerpiece of this grant was our 4.1T ultra-high field whole-body nuclear magnetic resonance system and the newly acquired state-of-the-art, heart and head dedicated 3T clinical MRI system. We have successfully upgraded the equipment for the 4.1T system so that it is now state-of-the-art with new gradient and radio frequency amplifiers. We also purchase a unique In Vivo EKG monitoring unit that will permit tracking clinical quality EKG signals while the patient is in a high field MR scanner. Important upgrades of a peripheral vascular coil and a state-of-the-art clinical workstation for processing complex heart images were implemented. The most recent acquisition was the purchase of a state-of-the-art Philips 3T Intera clinical MRI system. This system is unique in that the magnet is only 5 1/2 feet long compare to over 12 feet long magnet of our 4.1T MRI system. The 3T MRI system is fully functional and its use and applications are already greatly benefiting the UAB with 200-300 micron resolution brain images and diagnostic quality MR angiography of coronary arteries in less than 5 minutes.

  12. Imaging Patterns in MRI in Recent Bone Injuries Following Negative or Inconclusive Plain Radiographs

    PubMed Central

    Sadineni, Raghu Teja; Bellapa, Narayan Chander; Velicheti, Sandeep

    2015-01-01

    Background Few bony injuries and most soft tissue injuries cannot be detected on plain radiography. Magnetic resonance imaging (MRI) can detect such occult bony injuries due to signal changes in bone marrow. In addition to excluding serious bony injuries, it can also identify tendon, ligament, cartilage and other soft tissue injuries and thus help in localizing the cause of morbidity. Aims and Objectives To determine the MRI imaging patterns in recent bone injuries (less than 4 weeks) following negative or inconclusive plain radiographs. To determine the role of MRI in recent fractures. Results Out of the 75 individuals with history of recent injury of less than 4 weeks duration, fracture line was demonstrated in 16 patients (21%) who had no obvious evidence of bone injury on plain radiographs. Bone contusion or bruising of the bone was demonstrated in 39 (52%) patients. This was the commonest abnormality detected in MRI. The remaining 20 patients did not show any obvious injury to the bone on MR imaging however, soft tissue injury could be demonstrated in 12 (16%) patients which show that the extent of soft tissue injury was relatively well demonstrated by MR imaging. The present study showed that occult injuries commonly occur at the Knee followed by Ankle, Wrist, Foot, Elbow, Leg, Hands, Hips & Spine. Conclusion The study showed that MR is efficient in the detection of occult bone injuries which are missed on radiography. Compared to radiographs, MRI clearly depicted the extent of injuries and associated soft tissue involvement. MRI demonstrates both acute and chronic injuries and also differentiates both, whereas radiography has poor sensitivity for acute injuries. Also, the soft tissue injuries like tendionous and ligamentous injuries cannot be identified on radiographs. PMID:26557590

  13. Functional MRI of long-term potentiation: imaging network plasticity

    PubMed Central

    Álvarez-Salvado, Efrén; Pallarés, Vicente; Moreno, Andrea; Canals, Santiago

    2014-01-01

    Neurons are able to express long-lasting and activity-dependent modulations of their synapses. This plastic property supports memory and conveys an extraordinary adaptive value, because it allows an individual to learn from, and respond to, changes in the environment. Molecular and physiological changes at the cellular level as well as network interactions are required in order to encode a pattern of synaptic activity into a long-term memory. While the cellular mechanisms linking synaptic plasticity to memory have been intensively studied, those regulating network interactions have received less attention. Combining high-resolution fMRI and in vivo electrophysiology in rats, we have previously reported a functional remodelling of long-range hippocampal networks induced by long-term potentiation (LTP) of synaptic plasticity in the perforant pathway. Here, we present new results demonstrating an increased bilateral coupling in the hippocampus specifically supported by the mossy cell commissural/associational pathway in response to LTP. This fMRI-measured increase in bilateral connectivity is accompanied by potentiation of the corresponding polysynaptically evoked commissural potential in the contralateral dentate gyrus and depression of the inactive convergent commissural pathway to the ipsilateral dentate. We review these and previous findings in the broader context of memory consolidation. PMID:24298154

  14. Non-invasive functional imaging of Cerebral Blood Volume with Vascular-Space-Occupancy (VASO) MRI

    PubMed Central

    Lu, Hanzhang; Hua, Jun; van Zijl, Peter C.M.

    2013-01-01

    Functional MRI (fMRI) based on changes in cerebral blood volume (CBV) can directly probe vasodilatation and vasoconstriction during brain activation or physiologic challenges, and can provide important insights into the mechanism of Blood-Oxygenation-Level-Dependent (BOLD) signal changes. At present, the most widely used CBV fMRI technique in humans is called Vascular-Space-Occupancy (VASO) MRI and this article provides a technical review of this method. VASO MRI utilizes T1 differences between blood and tissue to distinguish these two compartments within a voxel and uses blood-nulling inversion recovery sequence to yield an MR signal proportional to 1-CBV. As such, vasodilatation will result in a VASO signal decrease and vasoconstriction will have the reverse effect. The VASO technique can be performed dynamically with a temporal resolution comparable to several other fMRI methods such as BOLD or Arterial-Spin-Labeling (ASL), and is particularly powerful when conducted in conjunction with these complementary techniques. The pulse sequence and imaging parameters of VASO can be optimized such that the signal change is predominantly of CBV origin, but careful considerations should be taken to minimize other contributions, such as those from the BOLD effect, CBF, and CSF. Sensitivity of the VASO technique remains to be the primary disadvantage when compared to BOLD, but this technique is increasingly demonstrating utility in neuroscientific and clinical applications. PMID:23355392

  15. DCE-MRI in hepatocellular carcinoma-clinical and therapeutic image biomarker

    PubMed Central

    Chen, Bang-Bin; Shih, Tiffany Ting-Fang

    2014-01-01

    Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) enables tumor vascular physiology to be assessed. Within the tumor tissue, contrast agents (gadolinium chelates) extravasate from intravascular into the extravascular extracellular space (EES), which results in a signal increase on T1-weighted MRI. The rate of contrast agents extravasation to EES in the tumor tissue is determined by vessel leakiness and blood flow. Thus, the signal measured on DCE-MRI represents a combination of permeability and perfusion. The semi-quantitative analysis is based on the calculation of heuristic parameters that can be extracted from signal intensity-time curves. These enhancing curves can also be deconvoluted by mathematical modeling to extract quantitative parameters that may reflect tumor perfusion, vascular volume, vessel permeability and angiogenesis. Because hepatocellular carcinoma (HCC) is a hypervascular tumor, many emerging therapies focused on the inhibition of angiogenesis. DCE-MRI combined with a pharmacokinetic model allows us to produce highly reproducible and reliable parametric maps of quantitative parameters in HCC. Successful therapies change quantitative parameters of DCE-MRI, which may be used as early indicators of tumor response to anti-angiogenesis agents that modulate tumor vasculature. In the setting of clinical trials, DCE-MRI may provide relevant clinical information on the pharmacodynamic and biologic effects of novel drugs, monitor treatment response and predict survival outcome in HCC patients. PMID:24695624

  16. Copper oxide nanoparticles as contrast agents for MRI and ultrasound dual-modality imaging

    NASA Astrophysics Data System (ADS)

    Perlman, Or; Weitz, Iris S.; Azhari, Haim

    2015-08-01

    Multimodal medical imaging is gaining increased popularity in the clinic. This stems from the fact that data acquired from different physical phenomena may provide complementary information resulting in a more comprehensive picture of the pathological state. In this context, nano-sized contrast agents may augment the potential sensitivity of each imaging modality and allow targeted visualization of physiological points of interest (e.g. tumours). In this study, 7 nm copper oxide nanoparticles (CuO NPs) were synthesized and characterized. Then, in vitro and phantom specimens containing CuO NPs ranging from 2.4 to 320 μg · mL-1 were scanned, using both 9.4 T MRI and through-transmission ultrasonic imaging. The results show that the CuO NPs induce shortening of the magnetic T1 relaxation time on the one hand, and increase the speed of sound and ultrasonic attenuation coefficient on the other. Moreover, these visible changes are NP concentration-dependent. The change in the physical properties resulted in a substantial increase in the contrast-to-noise ratio (3.4-6.8 in ultrasound and 1.2-19.3 in MRI). In conclusion, CuO NPs are excellent candidates for MRI-ultrasound dual imaging contrast agents. They offer radiation-free high spatial resolution scans by MRI, and cost-effective high temporal resolution scans by ultrasound.

  17. Three-dimensional correlation of MR images to muscle tissue response for interventional MRI thermal ablation

    NASA Astrophysics Data System (ADS)

    Breen, Michael S.; Lancaster, Tanya L.; Lazebnik, Roee S.; Ashcroft, Andrik J.; Gamal Nour, Sherif; Lewin, Jonathan S.; Wilson, David L.

    2001-05-01

    We are treating tumors using radiofrequency (RF) ablation under interventional MRI (iMRI) guidance. We investigated the ability of MR to monitor the treated region by comparing MR thermal lesion images to cellular damage as seen histologically. Our new methodology allows 3D registration that should enable more accurate correlation than previous 2D methods. Using a low-field (0.2T) open magnet iMRI system for probe guidance, we applied RF ablation to the thigh muscle of four New Zealand White rabbits. To relate in vivo MR and histology images, we obtained intermediate ex vivo MR images and pictures of thick tissue slices obtained using a specially designed apparatus. Registration was done with a computer algorithm that matches tracks of needle fiducials placed near the tissue of interest. After registration, we determined the region inside the circular, hyperintense rim in MR closely corresponds to the region of necrosis as determined by histology on animals sacrificed 30 minutes after ablation. This is good evidence that iMRI images can be used for real-time feedback during thermal RF ablation treatments.

  18. Application of Good's buffers to pH imaging using hyperpolarized (13)C MRI.

    PubMed

    Flavell, Robert R; von Morze, Cornelius; Blecha, Joseph E; Korenchan, David E; Van Criekinge, Mark; Sriram, Renuka; Gordon, Jeremy W; Chen, Hsin-Yu; Subramaniam, Sukumar; Bok, Robert A; Wang, Zhen J; Vigneron, Daniel B; Larson, Peder E; Kurhanewicz, John; Wilson, David M

    2015-09-25

    N-(2-Acetamido)-2-aminoethanesulfonic acid (ACES), one of Good's buffers, was applied to pH imaging using hyperpolarized (13)C magnetic resonance spectroscopy. Rapid NMR- and MRI-based pH measurements were obtained by exploiting the sensitive pH-dependence of its (13)C chemical shift within the physiologic range.

  19. Neuroimaging of pediatric brain tumors: from basic to advanced magnetic resonance imaging (MRI).

    PubMed

    Panigrahy, Ashok; Blüml, Stefan

    2009-11-01

    In this review, the basic magnetic resonance concepts used in the imaging approach of a pediatric brain tumor are described with respect to different factors including understanding the significance of the patient's age. Also discussed are other factors directly related to the magnetic resonance scan itself including evaluating the location of the tumor, determining if the lesion is extra-axial or intra-axial, and evaluating the contrast characteristics of the lesion. Of note, there are key imaging features of pediatric brain tumors, which can give information about the cellularity of the lesion, which can then be confirmed with advanced magnetic resonance imaging (MRI) techniques. The second part of this review will provide an overview of the major advanced MRI techniques used in pediatric imaging, particularly, magnetic resonance diffusion, magnetic resonance spectroscopy, and magnetic resonance perfusion. The last part of the review will provide more specific information about the use of advanced magnetic resonance techniques in the evaluation of pediatric brain tumors.

  20. Cross-modality assessment and planning for pulmonary trunk treatment using CT and MRI imaging.

    PubMed

    Vitanovski, Dime; Tsymbal, Alexey; Ionasec, Razvan Ioan; Georgescu, Bogdan; Hubert, Martin; Taylor, Andrew; Schievano, Silvia; Zhou, Shaohua Kevin; Hornegger, Joachim; Comaniciu, Dorin

    2010-01-01

    Congenital heart defect is the primary cause of death in newborns, due to typically complex malformation of the cardiac system. The pulmonary valve and trunk are often affected and require complex clinical management and in most cases surgical or interventional treatment. While minimal invasive methods are emerging, non-invasive imaging-based assessment tools become crucial components in the clinical setting. For advanced evaluation and therapy planning purposes, cardiac Computed Tomography (CT) and cardiac Magnetic Resonance Imaging (cMRI) are important non-invasive investigation techniques with complementary properties. Although, characterized by high temporal resolution, cMRI does not cover the full motion of the pulmonary trunk. The sparse cMRI data acquired in this context include only one 3D scan of the heart in the end-diastolic phase and two 2D planes (long and short axes) over the whole cardiac cycle. In this paper we present a cross-modality framework for the evaluation of the pulmonary trunk, which combines the advantages of both, cardiac CT and cMRI. A patient-specific model is estimated from both modalities using hierarchical learning-based techniques. The pulmonary trunk model is exploited within a novel dynamic regression-based reconstruction to infer the incomplete cMRI temporal information. Extensive experiments performed on 72 cardiac CT and 74 cMRI sequences demonstrated the average speed of 110 seconds and accuracy of 1.4mm for the proposed approach. To the best of our knowledge this is the first dynamic model of the pulmonary trunk and right ventricle outflow track estimated from sparse 4D cMRI data.

  1. Cross-modality assessment and planning for pulmonary trunk treatment using CT and MRI imaging.

    PubMed

    Vitanovski, Dime; Tsymbal, Alexey; Ionasec, Razvan Ioan; Georgescu, Bogdan; Hubert, Martin; Taylor, Andrew; Schievano, Silvia; Zhou, Shaohua Kevin; Hornegger, Joachim; Comaniciu, Dorin

    2010-01-01

    Congenital heart defect is the primary cause of death in newborns, due to typically complex malformation of the cardiac system. The pulmonary valve and trunk are often affected and require complex clinical management and in most cases surgical or interventional treatment. While minimal invasive methods are emerging, non-invasive imaging-based assessment tools become crucial components in the clinical setting. For advanced evaluation and therapy planning purposes, cardiac Computed Tomography (CT) and cardiac Magnetic Resonance Imaging (cMRI) are important non-invasive investigation techniques with complementary properties. Although, characterized by high temporal resolution, cMRI does not cover the full motion of the pulmonary trunk. The sparse cMRI data acquired in this context include only one 3D scan of the heart in the end-diastolic phase and two 2D planes (long and short axes) over the whole cardiac cycle. In this paper we present a cross-modality framework for the evaluation of the pulmonary trunk, which combines the advantages of both, cardiac CT and cMRI. A patient-specific model is estimated from both modalities using hierarchical learning-based techniques. The pulmonary trunk model is exploited within a novel dynamic regression-based reconstruction to infer the incomplete cMRI temporal information. Extensive experiments performed on 72 cardiac CT and 74 cMRI sequences demonstrated the average speed of 110 seconds and accuracy of 1.4mm for the proposed approach. To the best of our knowledge this is the first dynamic model of the pulmonary trunk and right ventricle outflow track estimated from sparse 4D cMRI data. PMID:20879263

  2. Fusion of rat brain histology and MRI using weighted multi-image mutual information

    NASA Astrophysics Data System (ADS)

    Palm, Christoph; Penney, Graeme P.; Crum, William R.; Schnabel, Julia A.; Pietrzyk, Uwe; Hawkes, David J.

    2008-03-01

    Introduction - Fusion of histology and MRI is frequently demanded in biomedical research to study in vitro tissue properties in an in vivo reference space. Distortions and artifacts caused by cutting and staining of histological slices as well as differences in spatial resolution make even the rigid fusion a difficult task. State-of- the-art methods start with a mono-modal restacking yielding a histological pseudo-3D volume. The 3D information of the MRI reference is considered subsequently. However, consistency of the histology volume and consistency due to the corresponding MRI seem to be diametral goals. Therefore, we propose a novel fusion framework optimizing histology/histology and histology/MRI consistency at the same time finding a balance between both goals. Method - Direct slice-to-slice correspondence even in irregularly-spaced cutting sequences is achieved by registration-based interpolation of the MRI. Introducing a weighted multi-image mutual information metric (WI), adjacent histology and corresponding MRI are taken into account at the same time. Therefore, the reconstruction of the histological volume as well as the fusion with the MRI is done in a single step. Results - Based on two data sets with more than 110 single registrations in all, the results are evaluated quantitatively based on Tanimoto overlap measures and qualitatively showing the fused volumes. In comparison to other multi-image metrics, the reconstruction based on WI is significantly improved. We evaluated different parameter settings with emphasis on the weighting term steering the balance between intra- and inter-modality consistency.

  3. Globally optimal co-segmentation of three-dimensional pulmonary ¹H and hyperpolarized ³He MRI with spatial consistence prior.

    PubMed

    Guo, Fumin; Yuan, Jing; Rajchl, Martin; Svenningsen, Sarah; Capaldi, Dante P I; Sheikh, Khadija; Fenster, Aaron; Parraga, Grace

    2015-07-01

    Pulmonary imaging using hyperpolarized (3)He/(129)Xe gas is emerging as a new way to understand the regional nature of pulmonary ventilation abnormalities in obstructive lung diseases. However, the quantitative information derived is completely dependent on robust methods to segment both functional and structural/anatomical data. Here, we propose an approach to jointly segment the lung cavity from (1)H and (3)He pulmonary magnetic resonance images (MRI) by constraining the spatial consistency of the two segmentation regions, which simultaneously employs the image features from both modalities. We formulated the proposed co-segmentation problem as a coupled continuous min-cut model and showed that this combinatorial optimization problem can be solved globally and exactly by means of convex relaxation. In particular, we introduced a dual coupled continuous max-flow model to study the convex relaxed coupled continuous min-cut model under a primal and dual perspective. This gave rise to an efficient duality-based convex optimization algorithm. We implemented the proposed algorithm in parallel using general-purpose programming on graphics processing unit (GPGPU), which substantially increased its computational efficiency. Our experiments explored a clinical dataset of 25 subjects with chronic obstructive pulmonary disease (COPD) across a wide range of disease severity. The results showed that the proposed co-segmentation approach yielded superior performance compared to single-channel image segmentation in terms of precision, accuracy and robustness.

  4. Differential roles for parietal and frontal cortices in fixed versus evolving temporal expectations: Dissociating prior from posterior temporal probabilities with fMRI.

    PubMed

    Coull, Jennifer T; Cotti, Julien; Vidal, Franck

    2016-11-01

    The ability to predict when an event will occur allows us to respond optimally to that event. Temporal predictability can be either fixed (prior probability) or evolving (posterior probability), in which case it is dynamically updated as a function of the elapse of time itself ("hazard function"). We used fMRI to identify the brain regions involved in either form of temporal prediction, within a single experimental paradigm. Participants performed a cued reaction time (RT) task, in which the target appeared after one of four intervals ("foreperiods") that was either predictable (temporal condition) or variable (neutral condition). As expected, RTs were faster in temporal versus neutral conditions, indicating the behavioural benefit of fixed temporal predictability. RTs also got faster as a function of foreperiod in the neutral, but not temporal, condition, reflecting the evolving temporal predictability of the hazard function. We confirmed that left inferior parietal cortex was preferentially activated by the fixed temporal predictability of temporal (versus neutral) cues. Then, by directly comparing how activity varied as a function of foreperiod in the neutral versus time conditions, we identified the neural substrates of the changes in temporal probability defined by the hazard function, while simultaneously controlling for changes related simply to the elapse of time itself. Whole-brain fMRI analyses (independently confirmed by anatomically guided ROI analyses) showed that activity in left inferior parietal cortex tracked the evolving temporal probabilities of the hazard function. ROI analysis further revealed a similar role for right inferior frontal cortex. Our data highlight a key role for left parietal cortex in instantiating the behavioural benefits of temporal predictability, whether predictions are fixed or dynamically evolving.

  5. Activatable molecular MRI nanoprobe for tumor cell imaging based on gadolinium oxide and iron oxide nanoparticle.

    PubMed

    Li, Jingjing; Wang, Shan; Wu, Chen; Dai, Yue; Hou, Pingfu; Han, Cuiping; Xu, Kai

    2016-12-15

    Activatable molecular MRI nanoprobe for intracellular GSH sensing was designed. As an alternative to "always on" nanoprobe, activatable imaging nanoprobes which are designed to amplify or boost imaging signals only in response to the targets have attracted more and more attention. In this paper, we designed a novel activatable molecular magnetic resonance imaging (MRI) nanoprobe for tumor cell recognization based on a MRI signal variation induced by the distance change between T1 and T2 contrast agents (CAs) in the presence of glutathione (GSH). To achieve this aim, carboxyl group functionalized iron oxide nanoparticles (Fe3O4 NPs) and polyethylene glycol-coated gadolinium oxide (PEG-Gd2O3) NPs as T2 and T1 MRI CA were connected by cystamine which contains a disulfide linkage. Transmission electron microscopic (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometer (EDS), fourier transform infrared spectroscopy (FT-IR), mass spectra and (1)H nuclear magnetic resonance spectroscopy ((1)H NMR) were introduced for their characterizations. The formation of Fe3O4-cystamine-Gd2O3 (Fe3O4-SS-Gd2O3) nanocomplex resulted in a quenched T1 signal due to the near proximity of PEG-Gd2O3 NPs to Fe3O4 NPs and a "light-up" T1 signal with the cleavage of disulfide bond in the presence of GSH. These results provide not only an easy way to realize MRI of tumor cells based on the overexpressed intracellular GSH level, but also a new insight for the design of activatable MRI nanoprobe. PMID:27501342

  6. [From anatomy to image: the cranial nerves at MRI].

    PubMed

    Conforti, Renata; Marrone, Valeria; Sardaro, Angela; Faella, Pierluigi; Grassi, Roberta; Cappabianca, Salvatore

    2013-01-01

    In this article, we review the expected course of each of the 12 cranial nerves. Traditional magnetic resonance imaging depicts only the larger cranial nerves but SSFP sequences of magnetic resonance imaging are capable of depicting the cisternal segments of 12 cranial nerves and also provide submillimetric spatial resolution.

  7. Free-breathing 3D cardiac MRI using iterative image-based respiratory motion correction.

    PubMed

    Moghari, Mehdi H; Roujol, Sébastien; Chan, Raymond H; Hong, Susie N; Bello, Natalie; Henningsson, Markus; Ngo, Long H; Goddu, Beth; Goepfert, Lois; Kissinger, Kraig V; Manning, Warren J; Nezafat, Reza

    2013-10-01

    Respiratory motion compensation using diaphragmatic navigator gating with a 5 mm gating window is conventionally used for free-breathing cardiac MRI. Because of the narrow gating window, scan efficiency is low resulting in long scan times, especially for patients with irregular breathing patterns. In this work, a new retrospective motion compensation algorithm is presented to reduce the scan time for free-breathing cardiac MRI that increasing the gating window to 15 mm without compromising image quality. The proposed algorithm iteratively corrects for respiratory-induced cardiac motion by optimizing the sharpness of the heart. To evaluate this technique, two coronary MRI datasets with 1.3 mm(3) resolution were acquired from 11 healthy subjects (seven females, 25 ± 9 years); one using a navigator with a 5 mm gating window acquired in 12.0 ± 2.0 min and one with a 15 mm gating window acquired in 7.1 ± 1.0 min. The images acquired with a 15 mm gating window were corrected using the proposed algorithm and compared to the uncorrected images acquired with the 5 and 15 mm gating windows. The image quality score, sharpness, and length of the three major coronary arteries were equivalent between the corrected images and the images acquired with a 5 mm gating window (P-value > 0.05), while the scan time was reduced by a factor of 1.7. PMID:23132549

  8. Small BODIPY Probes for Combined Dual (19) F MRI and Fluorescence Imaging.

    PubMed

    Huynh, Anh Minh; Müller, Andreas; Kessler, Sonja M; Henrikus, Sarah; Hoffmann, Caroline; Kiemer, Alexandra K; Bücker, Arno; Jung, Gregor

    2016-07-19

    The combination of the two complementary imaging modalities (19) F magnetic resonance imaging (MRI) and fluorescence imaging (FLI) possesses high potential for biological and medical applications. Herein we report the first design, synthesis, dual detection validation, and cytotoxic testing of four promising BODIPY dyes for dual (19) F MRI-fluorescence detection. Using straightforward Steglich reactions, small fluorinated alcohols were easily covalently tethered to a BODIPY dye in high yields, leaving its fluorescence properties unaffected. The synthesized compounds were analyzed with various techniques to demonstrate their potential utility in dual imaging. As expected, the chemically and magnetically equivalent trifluoromethyl groups of the agents exhibited a single NMR signal. The determined longitudinal relaxation times T1 and the transverse relaxation times T2 , both in the lower second range, enabled the imaging of four compounds in vitro. The most auspicious dual (19) F MRI-fluorescence agent was also successfully imaged in a mouse post-mortem within a 9.4 T small-animal tomograph. Toxicological assays with human cells (primary HUVEC and HepG2 cell line) also indicated the possibility for animal testing. PMID:27347843

  9. Registration of structurally dissimilar images in MRI-based brachytherapy

    NASA Astrophysics Data System (ADS)

    Berendsen, F. F.; Kotte, A. N. T. J.; de Leeuw, A. A. C.; Jürgenliemk-Schulz, I. M.; Viergever, M. A.; Pluim, J. P. W.

    2014-08-01

    A serious challenge in image registration is the accurate alignment of two images in which a certain structure is present in only one of the two. Such topological changes are problematic for conventional non-rigid registration algorithms. We propose to incorporate in a conventional free-form registration framework a geometrical penalty term that minimizes the volume of the missing structure in one image. We demonstrate our method on cervical MR images for brachytherapy. The intrapatient registration problem involves one image in which a therapy applicator is present and one in which it is not. By including the penalty term, a substantial improvement in the surface distance to the gold standard anatomical position and the residual volume of the applicator void are obtained. Registration of neighboring structures, i.e. the rectum and the bladder is generally improved as well, albeit to a lesser degree.

  10. MRI and FDG PET/CT imaging manifestations of cardiac sarcoidosis.

    PubMed

    Lu, Yang; Sweiss, Nadera J

    2015-12-01

    A 52-year-old man had biopsy-proven sarcoidosis of mediastinal lymph nodes. Cardiac sarcoidosis was confirmed on cardiac MRI with typical imaging features as delayed gadolinium enhancement. Follow-up FDG PET/CT with a 3-day pretest diet modification showed suppression of overall myocardial uptake of FDG but with multifocal abnormal FDG uptake in the myocardium regions corresponding to the previous MRI findings. Additional noncardiac active sarcoidosis involving multiple organ and lymph nodes were also visualized on FDG PET/CT. PMID:26544904

  11. Robust interferometric imaging via prior-less phase recovery: redundant spacing calibration with generalized closure phases

    NASA Astrophysics Data System (ADS)

    Kurien, Binoy G.; Ashcom, Jonathan B.; Shah, Vinay N.; Rachlin, Yaron; Tarokh, Vahid

    2016-09-01

    Atmospheric turbulence presents a fundamental challenge to Fourier phase recovery in optical interferometry. Typical reconstruction algorithms employ Bayesian inference techniques which rely on prior knowledge of the scene under observation. In contrast, Redundant Spacing Calibration (RSC) algorithms employ redundancy in the baselines of the interferometric array to directly expose the contribution of turbulence, thereby enabling phase recovery for targets of arbitrary and unknown complexity. Traditionally RSC algorithms have been applied directly to single-exposure measurements, which are reliable only at high photon flux in general. In scenarios of low photon flux, such as those arising in the observation of dim objects in space, one must instead rely on time-averaged, atmosphere-invariant quantities such as the bispectrum. In this paper, we develop a novel RSC-based algorithm for prior-less phase recovery in which we generalize the bispectrum to higher-order atmosphere-invariants (n-spectra) for improved sensitivity. We provide a strategy for selection of a high-SNR set of n-spectra using the graph-theoretic notion of the minimum cycle basis. We also discuss a key property of this set (wrap-invariance), which then enables reliable application of standard linear estimation techniques to recover the Fourier phases from the 2π-wrapped n-spectra phases. For validation, we analyze the expected shot-noise-limited performance of our algorithm for both pairwise and Fizeau interferometric architectures, and corroborate this analysis with simulation results showing performance near an atmosphere-oracle Cramer-Rao bound. Lastly, we apply techniques from the field of compressed sensing to perform image reconstruction from the estimated complex visibilities.

  12. A prior knowledge model for multidimensional striping noise compensation in hyperspectral imaging devices

    NASA Astrophysics Data System (ADS)

    Meza, Pablo; Pezoa, Jorge E.; Parra, Francisca; Torres, Sergio N.

    2012-09-01

    In this paper, a prior knowledge model is proposed in order to increase the effectiveness of a multidimensional striping noise compensation (SNC) algorithm. This is accomplished by considering an optoelectronic approach, thereby generating a more accurate mathematical representation of the hyperspectral acquisition process. The proposed model includes knowledge on the system spectral response, which can be obtained by means of an input with known spectral radiation. Further, the model also considers the dependence of the noise structure on the analog-digital conversion process, that is, schemes such as active-pixel sensor (APS) and passive-pixel sensor (PPS) have been considered. Finally, the model takes advantage of the degree of crosstalk between consecutive bands in order to determinate how much of this spectral information is contributing to the read out data obtained in a particular band. All prior knowledge is obtained by a series of experimental analysis, and then integrated into the model. After estimating the required parameters, the applicability of the multidimensional SNC is illustrated by compensating for stripping noise in hyperspectral images acquired using an experimental setup. A laboratory prototype, based on both a Photonfocus Hurricane hyperspectral camera and a Xeva Xenics NIR hyperspectral camera, has been implemented to acquire data in the range of 400-1000 [nm] and 900-1700 [nm], respectively. Also, a mobile platform has been used to simulate and synchronize the scanning procedure of the cameras and an uniform tungsten lamp has been installed to ensure an equal spectral radiance between the different bands for calibration purpose.

  13. MRI Mode Programming for Safe Magnetic Resonance Imaging in Patients With a Magnetic Resonance Conditional Cardiac Device.

    PubMed

    Nakai, Toshiko; Kurokawa, Sayaka; Ikeya, Yukitoshi; Iso, Kazuki; Takahashi, Keiko; Sasaki, Naoko; Ashino, Sonoko; Okubo, Kimie; Okumura, Yasuo; Kunimoto, Satoshi; Watanabe, Ichiro; Hirayama, Atsushi

    2016-01-01

    Although diagnostically indispensable, magnetic resonance imaging (MRI) has been, until recently, contraindicated in patients with an implantable cardiac device. MR conditional cardiac devices are now widely used, but the mode programming needed for safe MRI has yet to be established. We reviewed the details of 41 MRI examinations of patients with a MR conditional device. There were no associated adverse events. However, in 3 cases, paced beats competed with the patient's own beats during the MRI examination. We describe 2 of the 3 specific cases because they illustrate these potentially risky situations: a case in which the intrinsic heart rate increased and another in which atrial fibrillation occurred. Safe MRI in patients with an MR conditional device necessitates detailed MRI mode programming. The MRI pacing mode should be carefully and individually selected.

  14. An Atlas-Based Electron Density Mapping Method for Magnetic Resonance Imaging (MRI)-Alone Treatment Planning and Adaptive MRI-Based Prostate Radiation Therapy

    SciTech Connect

    Dowling, Jason A.; Lambert, Jonathan; Parker, Joel; Salvado, Olivier; Fripp, Jurgen; Capp, Anne; Wratten, Chris; Denham, James W.; Greer, Peter B.

    2012-05-01

    Purpose: Prostate radiation therapy dose planning directly on magnetic resonance imaging (MRI) scans would reduce costs and uncertainties due to multimodality image registration. Adaptive planning using a combined MRI-linear accelerator approach will also require dose calculations to be performed using MRI data. The aim of this work was to develop an atlas-based method to map realistic electron densities to MRI scans for dose calculations and digitally reconstructed radiograph (DRR) generation. Methods and Materials: Whole-pelvis MRI and CT scan data were collected from 39 prostate patients. Scans from 2 patients showed significantly different anatomy from that of the remaining patient population, and these patients were excluded. A whole-pelvis MRI atlas was generated based on the manually delineated MRI scans. In addition, a conjugate electron-density atlas was generated from the coregistered computed tomography (CT)-MRI scans. Pseudo-CT scans for each patient were automatically generated by global and nonrigid registration of the MRI atlas to the patient MRI scan, followed by application of the same transformations to the electron-density atlas. Comparisons were made between organ segmentations by using the Dice similarity coefficient (DSC) and point dose calculations for 26 patients on planning CT and pseudo-CT scans. Results: The agreement between pseudo-CT and planning CT was quantified by differences in the point dose at isocenter and distance to agreement in corresponding voxels. Dose differences were found to be less than 2%. Chi-squared values indicated that the planning CT and pseudo-CT dose distributions were equivalent. No significant differences (p > 0.9) were found between CT and pseudo-CT Hounsfield units for organs of interest. Mean {+-} standard deviation DSC scores for the atlas-based segmentation of the pelvic bones were 0.79 {+-} 0.12, 0.70 {+-} 0.14 for the prostate, 0.64 {+-} 0.16 for the bladder, and 0.63 {+-} 0.16 for the rectum

  15. Synergistic role of simultaneous PET/MRI-MRS in soft tissue sarcoma metabolism imaging.

    PubMed

    Zhang, Xiaomeng; Chen, Yen-Lin E; Lim, Ruth; Huang, Chuan; Chebib, Ivan A; El Fakhri, Georges

    2016-04-01

    The primary objective of this study was to develop and validate simultaneous PET/MRI-MRS as a novel biological image-guided approach to neoadjuvant radiotherapy (RT) and/or chemoradiation (chemoRT) in soft tissue sarcomas (STS). A patient with sarcoma of the right thigh underwent PET/MRI scan before and after neoadjuvant (preoperative) radiotherapy. The magnetic resonance imaging (MRI) and 2-deoxy-2-[fluorine-18]-fluoro-D-glucose-Positron Emission Tomography ((18)F-FDG-PET) scans were performed simultaneously. In the post-radiation scan, magnetic resonance spectroscopy (MRS) was subsequently acquired with volume of interest positioned in a residual hyper-metabolic region detected by PET. Post-radiation PET/MRI showed a residual T2-hyperintense mass with significantly reduced (18)F-FDG-uptake, compatible with near complete response to radiotherapy. However, a small region of residual high (18)F-FDG uptake was detected at the tumor margin. MRS of this region had similar metabolite profile as normal tissue, and was thus considered false positive on PET scan. Pathology results were obtained after surgery for confirmation of imaging findings.

  16. Real-time 3D imaging of microstructure growth in battery cells using indirect MRI.

    PubMed

    Ilott, Andrew J; Mohammadi, Mohaddese; Chang, Hee Jung; Grey, Clare P; Jerschow, Alexej

    2016-09-27

    Lithium metal is a promising anode material for Li-ion batteries due to its high theoretical specific capacity and low potential. The growth of dendrites is a major barrier to the development of high capacity, rechargeable Li batteries with lithium metal anodes, and hence, significant efforts have been undertaken to develop new electrolytes and separator materials that can prevent this process or promote smooth deposits at the anode. Central to these goals, and to the task of understanding the conditions that initiate and propagate dendrite growth, is the development of analytical and nondestructive techniques that can be applied in situ to functioning batteries. MRI has recently been demonstrated to provide noninvasive imaging methodology that can detect and localize microstructure buildup. However, until now, monitoring dendrite growth by MRI has been limited to observing the relatively insensitive metal nucleus directly, thus restricting the temporal and spatial resolution and requiring special hardware and acquisition modes. Here, we present an alternative approach to detect a broad class of metallic dendrite growth via the dendrites' indirect effects on the surrounding electrolyte, allowing for the application of fast 3D (1)H MRI experiments with high resolution. We use these experiments to reconstruct 3D images of growing Li dendrites from MRI, revealing details about the growth rate and fractal behavior. Radiofrequency and static magnetic field calculations are used alongside the images to quantify the amount of the growing structures.

  17. Improved registration of DCE-MR images of the liver using a prior segmentation of the region of interest

    NASA Astrophysics Data System (ADS)

    Zhang, Tian; Li, Zhang; Runge, Jurgen H.; Lavini, Cristina; Stoker, Jaap; van Gulik, Thomas; van Vliet, Lucas J.; Vos, Frans M.

    2016-03-01

    In Dynamic Contrast-Enhanced MRI (DCE-MRI) of the liver, a series of images is acquired over a period of 20 minutes. Due to the patient's breathing, the liver is subject to a substantial displacement between acquisitions. Furthermore, due to its location in the abdomen, the liver also undergoes marked deformation. The large deformations combined with variation in image contrast make accurate liver registration challenging. We present a registration framework that incorporates a liver segmentation to improve the registration accuracy. The segmented liver serves as region-of-interest to our in-house developed registration method called ALOST (autocorrelation of local image structure). ALOST is a continuous optimization method that uses local phase features to overcome space-variant intensity distortions. The proposed framework can confine the solution field to the liver and allow for ALOST to obtain a more accurate solution. For the segmentation part, we use a level-set method to delineate the liver in a so-called contrast enhancement map. This map is obtained by computing the difference between the last and registered first volume from the DCE series. Subsequently, we slightly dilate the segmentation, and apply it as the mask to the other DCE-MRI volumes during registration. It is shown that the registration result becomes more accurate compared with the original ALOST approach.

  18. Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: A feasibility study

    PubMed Central

    Cai, Jing; Chang, Zheng; Wang, Zhiheng; Paul Segars, William; Yin, Fang-Fang

    2011-01-01

    Purpose: Four-dimensional computed tomography (4D-CT) has been widely used in radiation therapy to assess patient-specific breathing motion for determining individual safety margins. However, it has two major drawbacks: low soft-tissue contrast and an excessive imaging dose to the patient. This research aimed to develop a clinically feasible four-dimensional magnetic resonance imaging (4D-MRI) technique to overcome these limitations. Methods: The proposed 4D-MRI technique was achieved by continuously acquiring axial images throughout the breathing cycle using fast 2D cine-MR imaging, and then retrospectively sorting the images by respiratory phase. The key component of the technique was the use of body area (BA) of the axial MR images as an internal respiratory surrogate to extract the breathing signal. The validation of the BA surrogate was performed using 4D-CT images of 12 cancer patients by comparing the respiratory phases determined using the BA method to those determined clinically using the Real-time position management (RPM) system. The feasibility of the 4D-MRI technique was tested on a dynamic motion phantom, the 4D extended Cardiac Torso (XCAT) digital phantom, and two healthy human subjects. Results: Respiratory phases determined from the BA matched closely to those determined from the RPM: mean (±SD) difference in phase: −3.9% (±6.4%); mean (±SD) absolute difference in phase: 10.40% (±3.3%); mean (±SD) correlation coefficient: 0.93 (±0.04). In the motion phantom study, 4D-MRI clearly showed the sinusoidal motion of the phantom; image artifacts observed were minimal to none. Motion trajectories measured from 4D-MRI and 2D cine-MRI (used as a reference) matched excellently: the mean (±SD) absolute difference in motion amplitude: −0.3 (±0.5) mm. In the 4D-XCAT phantom study, the simulated “4D-MRI” images showed good consistency with the original 4D-XCAT phantom images. The motion trajectory of the hypothesized “tumor” matched

  19. Angiomia Imaging and Diagnostics, Angiography and Functional MRI

    MedlinePlus

    ... administer these procedures and interpret the results. As technology and understanding of disease pathology evolves, combinations of ... integrated and layered approach. In some cases, imaging technology, which has been around for a decade or ...

  20. Image homogenization using pre-emphasis method for high field MRI

    PubMed Central

    Li, Ye; Wang, Chunsheng; Yu, Baiying; Vigneron, Daniel; Chen, Wei

    2013-01-01

    Radiofrequency (RF) field (B1) inhomogeneity due to shortened wavelength at high field is a major cause of magnetic resonance imaging (MRI) nonuniformity in high dielectric biological samples (e.g., human body). In this work, we propose a method to improve the B1 and MRI homogeneity by using pre-emphasized non-uniform B1 distribution. The intrinsic B1 distribution that could be generated by a RF volume coil, specifically a microstrip transmission line (MTL) coil used in this work, was pre-emphasized in the sample’s periphery region of interest to compensate for the central brightness induced by high frequency interference effect due to shortened wave length. This pre-emphasized non-uniform B1 can be realized by varying the parameters of microstrip elements, such as the substrate thickness of MTL volume coil. Both numerical simulation and phantom MR imaging studies were carried out to investigate the feasibility and merit of the proposed method in achieving homogeneous MR images. The simulation results demonstrate that by using a pre-emphasized B1 distribution generated by the MTL volume coil, relatively uniform B1 distribution and homogeneous MR image (98% homogeneity) within the spherical phantom (15 cm diameter) were achieved with 4.5 mm thickness. The B1 and MRI intensity distributions of a 16-element MTL volume coil with fixed substrate thickness and five varied saline loads were modeled and experimentally tested. Similar results from both simulation and experiments were obtained, suggesting substantial improvements of B1 and MRI homogeneities within the phantom containing 125 mM saline. The overall results demonstrate an efficient B1 shimming approach for improving high field MRI. PMID:24040618

  1. Reprint of "Quantitative evaluation of brain development using anatomical MRI and diffusion tensor imaging".

    PubMed

    Oishi, Kenichi; Faria, Andreia V; Yoshida, Shoko; Chang, Linda; Mori, Susumu

    2014-02-01

    The development of the brain is structure-specific, and the growth rate of each structure differs depending on the age of the subject. Magnetic resonance imaging (MRI) is often used to evaluate brain development because of the high spatial resolution and contrast that enable the observation of structure-specific developmental status. Currently, most clinical MRIs are evaluated qualitatively to assist in the clinical decision-making and diagnosis. The clinical MRI report usually does not provide quantitative values that can be used to monitor developmental status. Recently, the importance of image quantification to detect and evaluate mild-to-moderate anatomical abnormalities has been emphasized because these alterations are possibly related to several psychiatric disorders and learning disabilities. In the research arena, structural MRI and diffusion tensor imaging (DTI) have been widely applied to quantify brain development of the pediatric population. To interpret the values from these MR modalities, a "growth percentile chart," which describes the mean and standard deviation of the normal developmental curve for each anatomical structure, is required. Although efforts have been made to create such a growth percentile chart based on MRI and DTI, one of the greatest challenges is to standardize the anatomical boundaries of the measured anatomical structures. To avoid inter- and intra-reader variability about the anatomical boundary definition, and hence, to increase the precision of quantitative measurements, an automated structure parcellation method, customized for the neonatal and pediatric population, has been developed. This method enables quantification of multiple MR modalities using a common analytic framework. In this paper, the attempt to create an MRI- and a DTI-based growth percentile chart, followed by an application to investigate developmental abnormalities related to cerebral palsy, Williams syndrome, and Rett syndrome, have been introduced. Future

  2. Quantitative evaluation of brain development using anatomical MRI and diffusion tensor imaging.

    PubMed

    Oishi, Kenichi; Faria, Andreia V; Yoshida, Shoko; Chang, Linda; Mori, Susumu

    2013-11-01

    The development of the brain is structure-specific, and the growth rate of each structure differs depending on the age of the subject. Magnetic resonance imaging (MRI) is often used to evaluate brain development because of the high spatial resolution and contrast that enable the observation of structure-specific developmental status. Currently, most clinical MRIs are evaluated qualitatively to assist in the clinical decision-making and diagnosis. The clinical MRI report usually does not provide quantitative values that can be used to monitor developmental status. Recently, the importance of image quantification to detect and evaluate mild-to-moderate anatomical abnormalities has been emphasized because these alterations are possibly related to several psychiatric disorders and learning disabilities. In the research arena, structural MRI and diffusion tensor imaging (DTI) have been widely applied to quantify brain development of the pediatric population. To interpret the values from these MR modalities, a "growth percentile chart," which describes the mean and standard deviation of the normal developmental curve for each anatomical structure, is required. Although efforts have been made to create such a growth percentile chart based on MRI and DTI, one of the greatest challenges is to standardize the anatomical boundaries of the measured anatomical structures. To avoid inter- and intra-reader variability about the anatomical boundary definition, and hence, to increase the precision of quantitative measurements, an automated structure parcellation method, customized for the neonatal and pediatric population, has been developed. This method enables quantification of multiple MR modalities using a common analytic framework. In this paper, the attempt to create an MRI- and a DTI-based growth percentile chart, followed by an application to investigate developmental abnormalities related to cerebral palsy, Williams syndrome, and Rett syndrome, have been introduced. Future

  3. Role of Percutaneous Image Guided Biopsy in Spinal Lesions: Adequacy and Correlation with MRI Findings

    PubMed Central

    2016-01-01

    Introduction Although, MRI has increased our understanding of spinal pathologies, accurate diagnosis of spinal lesions need biopsy, so that early treatment can be initiated. Aim To evaluate the accuracy of biopsy, safety and yield of percutaneously done image guided spinal biopsy using a large bore needle and correlate between MRI findings and biopsy as well as the importance of various MRI findings in establishing the diagnosis. Materials and Methods All spinal lesions after clinical and MRI evaluation were subjected to Jamshidi Needle biopsy using 11 gauge needles. Biopsy material was sent for culture/sensitivity, AFB smear and histopathological examination. The outcome assessment included percentage of patients in whom diagnosis was changed after biopsy, yield in biopsy and complications of biopsy. MRI findings, biopsy findings and final diagnosis were correlated to know the sensitivity and specificity of MRI and biopsy diagnosis. Logistic regression analysis was used to study the importance of each of MRI findings in making a diagnosis. Results Forty five patients with spinal lesions underwent biopsy using an 11 gauge Jamshidi needle. Initial biopsy was inconclusive in 4 patients giving a positive yield in about 91.2% of cases and a repeat biopsy ensured conclusive report in all cases. Following biopsy there was a change in diagnosis in 8% cases. MRI showed sensitivity of 85.71% and specificity of 93.54% for the diagnosis of malignancy and sensitivity of 85.71% and specificity of 86.48% for the diagnosis of tuberculosis. In contrast, initial biopsy had sensitivity of 92.85% and specificity of 100% for the diagnosis of malignancy and sensitivity of 71.42% and specificity of 100 % for the diagnosis of infection. Logistic regression analysis showed good correlation between malignancy and posterior bugle in the vertebral body in the absence of a fracture (p = 0.007), involvement of pedicles and posterior elements (p = 0.001) and soft tissue extension (p = 0

  4. Visibility and artifacts of gold fiducial markers used for image guided radiation therapy of pancreatic cancer on MRI

    SciTech Connect

    Gurney-Champion, Oliver J.; Lens, Eelco; Horst, Astrid van der; Houweling, Antonetta C.; Tienhoven, Geertjan van; Bel, Arjan; Klaassen, Remy; Hooft, Jeanin E. van; Stoker, Jaap; Nederveen, Aart J.

    2015-05-15

    Purpose: In radiation therapy of pancreatic cancer, tumor alignment prior to each treatment fraction is improved when intratumoral gold fiducial markers (from here onwards: markers), which are visible on computed tomography (CT) and cone beam CT, are used. Visibility of these markers on magnetic resonance imaging (MRI) might improve image registration between CT and magnetic resonance (MR) images for tumor delineation purposes. However, concomitant image artifacts induced by markers are undesirable. The extent of visibility and artifact size depend on MRI-sequence parameters. The authors’ goal was to determine for various markers their potential to be visible and to generate artifacts, using measures that are independent of the MRI-sequence parameters. Methods: The authors selected ten different markers suitable for endoscopic placement in the pancreas and placed them into a phantom. The markers varied in diameter (0.28–0.6 mm), shape, and iron content (0%–0.5%). For each marker, the authors calculated T{sub 2}{sup ∗}-maps and ΔB{sub 0}-maps using MRI measurements. A decrease in relaxation time T{sub 2}{sup ∗} can cause signal voids, associated with visibility, while a change in the magnetic field B{sub 0} can cause signal shifts, which are associated with artifacts. These shifts inhibit accurate tumor delineation. As a measure for potential visibility, the authors used the volume of low T{sub 2}{sup ∗}, i.e., the volume for which T{sub 2}{sup ∗} differed from the background by >15 ms. As a measure for potential artifacts, the authors used the volume for which |ΔB{sub 0}| > 9.4 × 10{sup −8} T (4 Hz). To test whether there is a correlation between visibility and artifact size, the authors calculated the Spearman’s correlation coefficient (R{sub s}) between the volume of low T{sub 2}{sup ∗} and the volume of high |ΔB{sub 0}|. The authors compared the maps with images obtained using a clinical MR-sequence. Finally, for the best visible marker

  5. Low-Functioning Autism and Nonsyndromic Intellectual Disability: Magnetic Resonance Imaging (MRI) Findings.

    PubMed

    Erbetta, Alessandra; Bulgheroni, Sara; Contarino, Valeria Elisa; Chiapparini, Luisa; Esposito, Silvia; Annunziata, Silvia; Riva, Daria

    2015-10-01

    Previous neuroradiologic studies reported a high incidence of abnormalities in low-functioning autistic children. In this population, it is difficult to know which abnormality depends on autism itself and which is related to intellectual disability associated with autism. The aim of this study was to evaluate the frequency of neuroradiologic abnormalities in low-functioning autistic children compared to Intellectual Quotient and age-matched nonsyndromic children, using the same set of magnetic resonance imaging (MRI) sequences. MRI was rated as abnormal in 44% of autistic and 54% of children with intellectual disability. The main results were mega cisterna magna in autism and hypoplastic corpus callosum in intellectual disability. These abnormalities are morphologically visible signs of altered brain development. These findings, more frequent than expected, are not specific to the 2 conditions. Although MRI cannot be considered mandatory, it allows an in-depth clinical assessment in nonsyndromic intellectual-disabled and autistic children.

  6. A novel image analysis method based on Bayesian segmentation for event-related functional MRI

    NASA Astrophysics Data System (ADS)

    Huang, Lejian; Comer, Mary L.; Talavage, Thomas M.

    2008-02-01

    This paper presents the application of the expectation-maximization/maximization of the posterior marginals (EM/MPM) algorithm to signal detection for functional MRI (fMRI). On basis of assumptions for fMRI 3-D image data, a novel analysis method is proposed and applied to synthetic data and human brain data. Synthetic data analysis is conducted using two statistical noise models (white and autoregressive of order 1) and, for low contrast-to-noise ratio (CNR) data, reveals better sensitivity and specificity for the new method than for the traditional General Linear Model (GLM) approach. When applied to human brain data, functional activation regions are found to be consistent with those obtained using the GLM approach.

  7. Low-Functioning Autism and Nonsyndromic Intellectual Disability: Magnetic Resonance Imaging (MRI) Findings.

    PubMed

    Erbetta, Alessandra; Bulgheroni, Sara; Contarino, Valeria Elisa; Chiapparini, Luisa; Esposito, Silvia; Annunziata, Silvia; Riva, Daria

    2015-10-01

    Previous neuroradiologic studies reported a high incidence of abnormalities in low-functioning autistic children. In this population, it is difficult to know which abnormality depends on autism itself and which is related to intellectual disability associated with autism. The aim of this study was to evaluate the frequency of neuroradiologic abnormalities in low-functioning autistic children compared to Intellectual Quotient and age-matched nonsyndromic children, using the same set of magnetic resonance imaging (MRI) sequences. MRI was rated as abnormal in 44% of autistic and 54% of children with intellectual disability. The main results were mega cisterna magna in autism and hypoplastic corpus callosum in intellectual disability. These abnormalities are morphologically visible signs of altered brain development. These findings, more frequent than expected, are not specific to the 2 conditions. Although MRI cannot be considered mandatory, it allows an in-depth clinical assessment in nonsyndromic intellectual-disabled and autistic children. PMID:25895913

  8. Segmentation of MRI Brain Images with an Improved Harmony Searching Algorithm

    PubMed Central

    Yang, Zhang; Li, Guo; Weifeng, Ding

    2016-01-01

    The harmony searching (HS) algorithm is a kind of optimization search algorithm currently applied in many practical problems. The HS algorithm constantly revises variables in the harmony database and the probability of different values that can be used to complete iteration convergence to achieve the optimal effect. Accordingly, this study proposed a modified algorithm to improve the efficiency of the algorithm. First, a rough set algorithm was employed to improve the convergence and accuracy of the HS algorithm. Then, the optimal value was obtained using the improved HS algorithm. The optimal value of convergence was employed as the initial value of the fuzzy clustering algorithm for segmenting magnetic resonance imaging (MRI) brain images. Experimental results showed that the improved HS algorithm attained better convergence and more accurate results than those of the original HS algorithm. In our study, the MRI image segmentation effect of the improved algorithm was superior to that of the original fuzzy clustering method. PMID:27403428

  9. Segmentation of MRI Brain Images with an Improved Harmony Searching Algorithm.

    PubMed

    Yang, Zhang; Shufan, Ye; Li, Guo; Weifeng, Ding

    2016-01-01

    The harmony searching (HS) algorithm is a kind of optimization search algorithm currently applied in many practical problems. The HS algorithm constantly revises variables in the harmony database and the probability of different values that can be used to complete iteration convergence to achieve the optimal effect. Accordingly, this study proposed a modified algorithm to improve the efficiency of the algorithm. First, a rough set algorithm was employed to improve the convergence and accuracy of the HS algorithm. Then, the optimal value was obtained using the improved HS algorithm. The optimal value of convergence was employed as the initial value of the fuzzy clustering algorithm for segmenting magnetic resonance imaging (MRI) brain images. Experimental results showed that the improved HS algorithm attained better convergence and more accurate results than those of the original HS algorithm. In our study, the MRI image segmentation effect of the improved algorithm was superior to that of the original fuzzy clustering method. PMID:27403428

  10. Tissue Necrosis Monitoring for HIFU Ablation with T1 Contrast MRI Imaging

    NASA Astrophysics Data System (ADS)

    Hwang, San-Chao; Yao, Ching; Kuo, Ih-Yuan; Tsai, Wei-Cheng; Chang, Hsu

    2011-09-01

    In MR-guided HIFU ablation, MTC (Magnetization Transfer Contrast) or perfusion imaging is usually used after ablation to evaluate the ablated area based on the thermally induced necrosis contrast. In our MR-guided HIFU ablation study, a T1 contrast MRI scan sequence has been used to distinguish between necrotic and non-necrotic tissue. The ablation of porcine meat in-vitro and in-vivo pig leg muscle show that the necrotic area of T1 contrast MRI image coincides with the photographs of sliced specimen. The sequence is considerably easier to apply than MTC or perfusion imaging, while giving good necrosis contrast. In addition, no injection of contrast agent is needed, allowing multiple scans to be applied throughout the entire ablation procedure.

  11. Rapid dynamic radial MRI via reference image enforced histogram constrained reconstruction

    NASA Astrophysics Data System (ADS)

    Gaass, Thomas; Bauman, Grzegorz; Potdevin, Guillaume; Noël, Peter B.; Haase, Axel

    2014-03-01

    Exploiting spatio-temporal redundancies in sub-Nyquist sampled dynamic MRI for the suppression of undersampling artifacts was shown to be of great success. However, temporally averaged and blurred structures in image space composite data poses the risk of false information in the reconstruction. Within this work we assess the possibility of employing the composite image histogram as a measure of undersampling artifacts and as basis of their suppression. The proposed algorithm utilizes a histogram, computed from a composite image within a dynamically acquired interleaved radial MRI measurement as reference to compensate for the impact of undersampling in temporally resolved data without the incorporation of temporal averaging. In addition an image space regularization utilizing a single frame low-resolution reconstruction is implemented to enforce overall contrast fidelity. The performance of the approach was evaluated on a simulated radial dynamic MRI acquisition and on two functional in vivo radial cardiac acquisitions. Results demonstrate that the algorithm maintained contrast properties, details and temporal resolution in the images, while effectively suppressing undersampling artifacts.

  12. Iterative image reconstruction that includes a total variation regularization for radial MRI.

    PubMed

    Kojima, Shinya; Shinohara, Hiroyuki; Hashimoto, Takeyuki; Hirata, Masami; Ueno, Eiko

    2015-07-01

    This paper presents an iterative image reconstruction method for radial encodings in MRI based on a total variation (TV) regularization. The algebraic reconstruction method combined with total variation regularization (ART_TV) is implemented with a regularization parameter specifying the weight of the TV term in the optimization process. We used numerical simulations of a Shepp-Logan phantom, as well as experimental imaging of a phantom that included a rectangular-wave chart, to evaluate the performance of ART_TV, and to compare it with that of the Fourier transform (FT) method. The trade-off between spatial resolution and signal-to-noise ratio (SNR) was investigated for different values of the regularization parameter by experiments on a phantom and a commercially available MRI system. ART_TV was inferior to the FT with respect to the evaluation of the modulation transfer function (MTF), especially at high frequencies; however, it outperformed the FT with regard to the SNR. In accordance with the results of SNR measurement, visual impression suggested that the image quality of ART_TV was better than that of the FT for reconstruction of a noisy image of a kiwi fruit. In conclusion, ART_TV provides radial MRI with improved image quality for low-SNR data; however, the regularization parameter in ART_TV is a critical factor for obtaining improvement over the FT.

  13. Normalization of T2W-MRI prostate images using Rician a priori

    NASA Astrophysics Data System (ADS)

    Lemaître, Guillaume; Rastgoo, Mojdeh; Massich, Joan; Vilanova, Joan C.; Walker, Paul M.; Freixenet, Jordi; Meyer-Baese, Anke; Mériaudeau, Fabrice; Martí, Robert

    2016-03-01

    Prostate cancer is reported to be the second most frequently diagnosed cancer of men in the world. In practise, diagnosis can be affected by multiple factors which reduces the chance to detect the potential lesions. In the last decades, new imaging techniques mainly based on MRI are developed in conjunction with Computer-Aided Diagnosis (CAD) systems to help radiologists for such diagnosis. CAD systems are usually designed as a sequential process consisting of four stages: pre-processing, segmentation, registration and classification. As a pre-processing, image normalization is a critical and important step of the chain in order to design a robust classifier and overcome the inter-patients intensity variations. However, little attention has been dedicated to the normalization of T2W-Magnetic Resonance Imaging (MRI) prostate images. In this paper, we propose two methods to normalize T2W-MRI prostate images: (i) based on a Rician a priori and (ii) based on a Square-Root Slope Function (SRSF) representation which does not make any assumption regarding the Probability Density Function (PDF) of the data. A comparison with the state-of-the-art methods is also provided. The normalization of the data is assessed by comparing the alignment of the patient PDFs in both qualitative and quantitative manners. In both evaluation, the normalization using Rician a priori outperforms the other state-of-the-art methods.

  14. Iterative image reconstruction that includes a total variation regularization for radial MRI.

    PubMed

    Kojima, Shinya; Shinohara, Hiroyuki; Hashimoto, Takeyuki; Hirata, Masami; Ueno, Eiko

    2015-07-01

    This paper presents an iterative image reconstruction method for radial encodings in MRI based on a total variation (TV) regularization. The algebraic reconstruction method combined with total variation regularization (ART_TV) is implemented with a regularization parameter specifying the weight of the TV term in the optimization process. We used numerical simulations of a Shepp-Logan phantom, as well as experimental imaging of a phantom that included a rectangular-wave chart, to evaluate the performance of ART_TV, and to compare it with that of the Fourier transform (FT) method. The trade-off between spatial resolution and signal-to-noise ratio (SNR) was investigated for different values of the regularization parameter by experiments on a phantom and a commercially available MRI system. ART_TV was inferior to the FT with respect to the evaluation of the modulation transfer function (MTF), especially at high frequencies; however, it outperformed the FT with regard to the SNR. In accordance with the results of SNR measurement, visual impression suggested that the image quality of ART_TV was better than that of the FT for reconstruction of a noisy image of a kiwi fruit. In conclusion, ART_TV provides radial MRI with improved image quality for low-SNR data; however, the regularization parameter in ART_TV is a critical factor for obtaining improvement over the FT. PMID:25990884

  15. Repeated BOLD-fMRI imaging of deep brain stimulation responses in rats.

    PubMed

    Chao, Tzu-Hao Harry; Chen, Jyh-Horng; Yen, Chen-Tung

    2014-01-01

    Functional magnetic resonance imaging (fMRI) provides a picture of the global spatial activation pattern of the brain. Interest is growing regarding the application of fMRI to rodent models to investigate adult brain plasticity. To date, most rodent studies used an electrical forepaw stimulation model to acquire fMRI data, with α-chloralose as the anesthetic. However, α-chloralose is harmful to animals, and not suitable for longitudinal studies. Moreover, peripheral stimulation models enable only a limited number of brain regions to be studied. Processing between peripheral regions and the brain is multisynaptic, and renders interpretation difficult and uncertain. In the present study, we combined the medetomidine-based fMRI protocol (a noninvasive rodent fMRI protocol) with chronic implantation of an MRI-compatible stimulation electrode in the ventroposterior (VP) thalamus to repetitively sample thalamocortical responses in the rat brain. Using this model, we scanned the forebrain responses evoked by the VP stimulation repeatedly of individual rats over 1 week. Cortical BOLD responses were compared between the 2 profiles obtained at day1 and day8. We discovered reproducible frequency- and amplitude-dependent BOLD responses in the ipsilateral somatosensory cortex (S1). The S1 BOLD responses during the 2 sessions were conserved in maximal response amplitude, area size (size ratio from 0.88 to 0.91), and location (overlap ratio from 0.61 to 0.67). The present study provides a long-term chronic brain stimulation protocol for studying the plasticity of specific neural circuits in the rodent brain by BOLD-fMRI. PMID:24825464

  16. Calibration standard of body tissue with magnetic nanocomposites for MRI and X-ray imaging

    NASA Astrophysics Data System (ADS)

    Rahn, Helene; Woodward, Robert; House, Michael; Engineer, Diana; Feindel, Kirk; Dutz, Silvio; Odenbach, Stefan; StPierre, Tim

    2016-05-01

    We present a first study of a long-term phantom for Magnetic Resonance Imaging (MRI) and X-ray imaging of biological tissues with magnetic nanocomposites (MNC) suitable for 3-dimensional and quantitative imaging of tissues after, e.g. magnetically assisted cancer treatments. We performed a cross-calibration of X-ray microcomputed tomography (XμCT) and MRI with a joint calibration standard for both imaging techniques. For this, we have designed a phantom for MRI and X-ray computed tomography which represents biological tissue enriched with MNC. The developed phantoms consist of an elastomer with different concentrations of multi-core MNC. The matrix material is a synthetic thermoplastic gel, PermaGel (PG). The developed phantoms have been analyzed with Nuclear Magnetic Resonance (NMR) Relaxometry (Bruker minispec mq 60) at 1.4 T to obtain R2 transverse relaxation rates, with SQUID (Superconducting QUantum Interference Device) magnetometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to verify the magnetite concentration, and with XμCT and 9.4 T MRI to visualize the phantoms 3-dimensionally and also to obtain T2 relaxation times. A specification of a sensitivity range is determined for standard imaging techniques X-ray computed tomography (XCT) and MRI as well as with NMR. These novel phantoms show a long-term stability over several months up to years. It was possible to suspend a particular MNC within the PG reaching a concentration range from 0 mg/ml to 6.914 mg/ml. The R2 relaxation rates from 1.4 T NMR-relaxometry show a clear connection (R2=0.994) with MNC concentrations between 0 mg/ml and 4.5 mg/ml. The MRI experiments have shown a linear correlation of R2 relaxation and MNC concentrations as well but in a range between MNC concentrations of 0 mg/ml and 1.435 mg/ml. It could be shown that XμCT displays best moderate and high MNC concentrations. The sensitivity range for this particular XμCT apparatus yields from 0.569 mg/ml to 6.914 mg/ml. The

  17. Simultaneous imaging of locus coeruleus and substantia nigra with a quantitative neuromelanin MRI approach.

    PubMed

    Chen, Xiangchuan; Huddleston, Daniel E; Langley, Jason; Ahn, Sinyeob; Barnum, Christopher J; Factor, Stewart A; Levey, Allan I; Hu, Xiaoping

    2014-12-01

    Quantitative MRI of neuromelanin (NM) containing structures (referred to as NM-MRI) in the brainstem, namely the locus coeruleus (LC) and substantia nigra (SN), may assist with the early detection of Parkinson's disease (PD) and Alzheimer's disease (AD) as well as differential diagnosis in the early disease stages. In this study, two gradient echo (GRE) sequences with magnetization transfer contrast (MTC) preparation pulses were developed to simultaneously image the LC and SN. This has been a challenge with NM-MRI techniques used in previous studies due to the relatively high specific absorption rate (SAR) induced by these techniques. In addition, a semi-automated quantitative analysis scheme was applied to estimate volumes and contrast-to-noise ratios (CNR) of the LC and SN based on segmentation of both structures. Compared to a T1-weighted turbo spin echo (TSE) sequence typically used for simultaneous imaging of the LC and SN, the two GRE-MTC sequences exhibited improved performance in terms of higher sensitivity (in CNR) in imaging the SN and lower SAR during the scans. A multiple-measurement protocol was adopted as well so that motion degraded measurements could be removed and artifacts associated with motion could be corrected. The present approach has demonstrated advantages in image acquisition (lower SAR and higher sensitivity), image pre-processing (with motion correction) and quantitative image analysis (segmentation-based estimation of volume and CNR) when compared with existing NM-MRI approaches. This approach has potential for detection and monitoring of neurodegeneration in LC and SN in disease states including AD and PD.

  18. Automated localization of vertebra landmarks in MRI images

    NASA Astrophysics Data System (ADS)

    Pai, Akshay; Narasimhamurthy, Anand; Rao, V. S. Veeravasarapu; Vaidya, Vivek

    2011-03-01

    The identification of key landmark points in an MR spine image is an important step for tasks such as vertebra counting. In this paper, we propose a template matching based approach for automatic detection of two key landmark points, namely the second cervical vertebra (C2) and the sacrum from sagittal MR images. The approach is comprised of an approximate localization of vertebral column followed by matching with appropriate templates in order to detect/localize the landmarks. A straightforward extension of the work described here is an automated classification of spine section(s). It also serves as a useful building block for further automatic processing such as extraction of regions of interest for subsequent image processing and also in aiding the counting of vertebra.

  19. A Prospective Multi-Center Clinical Trial to Compare Efficiency, Accuracy and Safety Of the VisionScope Imaging System Compared to MRI and Diagnostic Arthroscopy

    PubMed Central

    Xerogeanes, John W.; Safran, Marc R.; Huber, Bryan; Mandelbaum, Bert R.; Robertson, William; Gambardella, Ralph A.

    2014-01-01

    Objectives: Until now, arthroscopic surgery has been the gold standard for the diagnosis of intra-articular pathology. When a patient presents with ongoing pain and/or disability despite non-operative care, MRI is commonly used as a diagnostic modality. To date, there is not a minimally-invasive option that can provide detailed information about the intra-articular pathology of a joint. VisionScope Imaging (VSI) is an office-based diagnostic modality that provides comprehensive real-time images and video of a joint with higher accuracy and reliability compared to static MR images. The purpose of this study was to compare the efficacy, accuracy and safety of VSI compared to MRI and surgical diagnostic arthroscopy. Methods: A prospective, blinded, multi-centered study was performed of all patients who had a routine surgical arthroscopy at one of the six participating clinical sites between July 2012 and May 2013. Patients were consented by the physician investigator at each site. Study inclusion criteria consisted of: suspected meniscal tears or articular cartilage damage. Patients were excluded from the study if they had (1) acute traumatic hemarthoses, (2) concomitant ligament injury, (3) active systemic infection, (4) allergy to silicone or any medication used during the procedure,. All patients had a MRI and a comprehensive physical exam prior to their surgical arthroscopy. Each patient underwent a MRI, VSI exam and surgical diagnostic arthroscopy. The attending physician completed standard forms comparing the VSI exam findings to the diagnostic arthroscopy findings on each patient. Two blinded experts unaffiliated with the study reviewed the VSI and MRI images. The arthroscopy served as the “control” comparison between the VSI and MRI findings. Results: There were 110 patients included in this study. The accuracy, sensitivity and specificity of VSI was equivalent to surgical diagnostic arthroscopy and more accurate than MRI (Table 1). When comparing VSI to

  20. Joint feature selection and classification using a Bayesian neural network with automatic relevance determination priors: potential use in CAD of medical imaging

    NASA Astrophysics Data System (ADS)

    Chen, Weijie; Zur, Richard M.; Giger, Maryellen L.

    2007-03-01

    Bayesian neural network (BNN) with automatic relevance determination (ARD) priors has the ability to assess the relevance of each input feature during network training. Our purpose is to investigate the potential use of BNN-with-ARD-priors for joint feature selection and classification in computer-aided diagnosis (CAD) of medical imaging. With ARD priors, each group of weights that connect an input feature to the hidden units is associated with a hyperparameter controlling the magnitudes of the weights. The hyperparameters and the weights are updated simultaneously during neural network training. A smaller hyperparameter will likely result in larger weight values and the corresponding feature will likely be more relevant to the output, and thus, to the classification task. For our study, a multivariate normal feature space is designed to include one feature with high classification performance in terms of both ideal observer and linear observer, two features with high ideal observer performance but low linear observer performance and 7 useless features. An exclusive-OR (XOR) feature space is designed to include 2 XOR features and 8 useless features. Our simulation results show that the ARD-BNN approach has the ability to select the optimal subset of features on the designed nonlinear feature spaces on which the linear approach fails. ARD-BNN has the ability to recognize features that have high ideal observer performance. Stepwise linear discriminant analysis (SWLDA) has the ability to select features that have high linear observer performance but fails to select features that have high ideal observer performance and low linear observer performance. The cross-validation results on clinical breast MRI data show that ARD-BNN yields statistically significant better performance than does the SWLDA-LDA approach. We believe that ARD-BNN is a promising method for pattern recognition in computer-aided diagnosis of medical imaging.

  1. Prioritization of brain MRI volumes using medical image perception model and tumor region segmentation.

    PubMed

    Mehmood, Irfan; Ejaz, Naveed; Sajjad, Muhammad; Baik, Sung Wook

    2013-10-01

    The objective of the present study is to explore prioritization methods in diagnostic imaging modalities to automatically determine the contents of medical images. In this paper, we propose an efficient prioritization of brain MRI. First, the visual perception of the radiologists is adapted to identify salient regions. Then this saliency information is used as an automatic label for accurate segmentation of brain lesion to determine the scientific value of that image. The qualitative and quantitative results prove that the rankings generated by the proposed method are closer to the rankings created by radiologists. PMID:24034739

  2. Ultra-fast MRI of the human brain with simultaneous multi-slice imaging

    NASA Astrophysics Data System (ADS)

    Feinberg, David A.; Setsompop, Kawin

    2013-04-01

    The recent advancement of simultaneous multi-slice imaging using multiband excitation has dramatically reduced the scan time of the brain. The evolution of this parallel imaging technique began over a decade ago and through recent sequence improvements has reduced the acquisition time of multi-slice EPI by over ten fold. This technique has recently become extremely useful for (i) functional MRI studies improving the statistical definition of neuronal networks, and (ii) diffusion based fiber tractography to visualize structural connections in the human brain. Several applications and evaluations are underway which show promise for this family of fast imaging sequences.

  3. Magnetic Resonance Imaging (MRI) Markers for MRI-Guided High-Dose-Rate Brachytherapy: Novel Marker-Flange for Cervical Cancer and Marker Catheters for Prostate Cancer

    SciTech Connect

    Schindel, Joshua; Muruganandham, Manickam; Pigge, F. Christopher; Anderson, James; Kim, Yusung

    2013-06-01

    Purpose: To present a novel marker-flange, addressing source-reconstruction uncertainties due to the artifacts of a titanium intracavitary applicator used for magnetic resonance imaging (MRI)-guided high-dose-rate (HDR) brachytherapy (BT); and to evaluate 7 different MRI marker agents used for interstitial prostate BT and intracavitary gynecologic HDR BT when treatment plans are guided by MRI. Methods and Materials: Seven MRI marker agents were analyzed: saline solution, Conray-60, copper sulfate (CuSO{sub 4}) (1.5 g/L), liquid vitamin E, fish oil, 1% agarose gel (1 g agarose powder per 100 mL distilled water), and a cobalt–chloride complex contrast (C4) (CoCl{sub 2}/glycine = 4:1). A plastic, ring-shaped marker-flange was designed and tested on both titanium and plastic applicators. Three separate phantoms were designed to test the marker-flange, interstitial catheters for prostate BT, and intracavitary catheters for gynecologic HDR BT. T1- and T2-weighted MRI were analyzed for all markers in each phantom and quantified as percentages compared with a 3% agarose gel background. The geometric accuracy of the MR signal for the marker-flange was measured using an MRI-CT fusion. Results: The CuSO{sub 4} and C4 markers on T1-weighted MRI and saline on T2-weighted MRI showed the highest signals. The marker-flange showed hyper-signals of >500% with CuSO{sub 4} and C4 on T1-weighted MRI and of >400% with saline on T2-weighted MRI on titanium applicators. On T1-weighted MRI, the MRI signal inaccuracies of marker-flanges were measured <2 mm, regardless of marker agents, and that of CuSO{sub 4} was 0.42 ± 0.14 mm. Conclusion: The use of interstitial/intracavitary markers for MRI-guided prostate/gynecologic BT was observed to be feasible, providing accurate source pathway reconstruction. The novel marker-flange can produce extremely intense, accurate signals, demonstrating its feasibility for gynecologic HDR BT.

  4. Single-Step Assembly of Multi-Modal Imaging Nanocarriers: MRI and Long-Wavelength Fluorescence Imaging

    PubMed Central

    Pinkerton, Nathalie M.; Gindy, Marian E.; Calero-DdelC, Victoria L.; Wolfson, Theodore; Pagels, Robert F.; Adler, Derek; Gao, Dayuan; Li, Shike; Wang, Ruobing; Zevon, Margot; Yao, Nan; Pacheco, Carlos; Therien, Michael J.; Rinaldi, Carlos; Sinko, Patrick J.

    2015-01-01

    MRI and NIR-active, multi-modal Composite NanoCarriers (CNCs) are prepared using a simple, one-step process, Flash NanoPrecipitation (FNP). The FNP process allows for the independent control of the hydrodynamic diameter, co-core excipient and NIR dye loading, and iron oxide-based nanocrystal (IONC) content of the CNCs. In the controlled precipitation process, 10 nm IONCs are encapsulated into poly(ethylene glycol) stabilized CNCs to make biocompatible T2 contrast agents. By adjusting the formulation, CNC size is tuned between 80 and 360 nm. Holding the CNC size constant at an intensity weighted average diameter of 99 ± 3 nm (PDI width 28 nm), the particle relaxivity varies linearly with encapsulated IONC content ranging from 66 to 533 mM-1s-1 for CNCs formulated with 4 to 16 wt% IONC. To demonstrate the use of CNCs as in vivo MRI contrast agents, CNCs are surface functionalized with liver targeting hydroxyl groups. The CNCs enable the detection of 0.8 mm3 non-small cell lung cancer metastases in mice livers via MRI. Incorporating the hydrophobic, NIR dye PZn3 into CNCs enables complementary visualization with long-wavelength fluorescence at 800 nm. In vivo imaging demonstrates the ability of CNCs to act both as MRI and fluorescent imaging agents. PMID:25925128

  5. High-quality four-dimensional cone-beam CT by deforming prior images

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Gu, Xuejun

    2013-01-01

    Due to a limited number of projections at each phase, severe view aliasing artifacts are present in four-dimensional cone beam computed tomography (4D-CBCT) when reconstruction is performed using conventional algorithms. In this work, we aim to obtain high-quality 4D-CBCT of lung cancer patients in radiation therapy by deforming the planning CT. The deformation vector fields (DVF) to deform the planning CT are estimated through matching the forward projection of the deformed prior image and measured on-treatment CBCT projection. The estimation of the DVF is formulated as an unconstrained optimization problem, where the objective function to be minimized is the sum of the squared difference between the forward projection of the deformed planning CT and the measured 4D-CBCT projection. A nonlinear conjugate gradient method is used to solve the DVF. As the number of the variables in the DVF is much greater than the number of measurements, the solution to such a highly ill-posed problem is very sensitive to the initials during the optimization process. To improve the estimation accuracy of DVF, we proposed a new strategy to obtain better initials for the optimization. In this strategy, 4D-CBCT is first reconstructed by total variation minimization. Demons deformable registration is performed to register the planning CT and the 4D-CBCT reconstructed by total variation minimization. The resulted DVF from demons registration is then used as the initial parameters in the optimization process. A 4D nonuniform rotational B-spline-based cardiac-torso (NCAT) phantom and a patient 4D-CBCT are used to evaluate the algorithm. Image quality of 4D-CBCT is substantially improved by using the proposed strategy in both NCAT phantom and patient studies. The proposed method has the potential to improve the temporal resolution of 4D-CBCT. Improved 4D-CBCT can better characterize the motion of lung tumors and will be a valuable tool for image-guided adaptive radiation therapy.

  6. Gray matter myelination of 1555 human brains using partial volume corrected MRI images

    PubMed Central

    Shafee, Rebecca; Buckner, Randy L.; Fischl, Bruce

    2014-01-01

    The myelin content of the cortex changes over the human lifetime and aberrant cortical myelination is associated with diseases such as schizophrenia and multiple sclerosis. Recently magnetic resonance imaging (MRI) techniques have shown potential in differentiating between myeloarchitectonically distinct cortical regions in vivo. Here we introduce a new algorithm for correcting partial volume effects present in mm-scale MRI images which was used to investigate the myelination pattern of the cerebral cortex in 1555 clinically normal subjects using the ratio of T1-weighted (T1w) and T2-weighted (T2w) MRI images. A significant linear cross-sectional age increase in T1w/T2w estimated myelin was detected across an 18 to 35 year age span (highest value of ~ 1%/year compared to mean T1w/T2w myelin value at 18 years). The cortex was divided at mid-thickness and the value of T1w/T2w myelin calculated for the inner and the outer layers separately. The increase in T1w/T2w estimated myelin occurs predominantly in the inner layer for most cortical regions. The ratio of the inner and outer layer T1w/T12w myelin was further validated using high-resolution in vivo MRI scans and also a high-resolution MRI scan of a postmortem brain. Additionally, the relationships between cortical thickness, curvature and T1w/T2w estimated myelin were found to be significant, although the relationships varied across the cortex. We discuss these observations as well as limitations of using the T1w/T2w ratio as an estimate of cortical myelin. PMID:25449739

  7. Ultra-small gadolinium oxide nanoparticles to image brain cancer cells in vivo with MRI.

    PubMed

    Faucher, Luc; Guay-Bégin, Andrée-Anne; Lagueux, Jean; Côté, Marie-France; Petitclerc, Eric; Fortin, Marc-André

    2011-01-01

    The majority of contrast agents used in magnetic resonance imaging (MRI) is based on the rare-earth element gadolinium. Gadolinium-based nanoparticles could find promising applications in pre-clinical diagnostic procedures of certain types of cancer, such as glioblastoma multiforme. This is one of the most malignant, lethal and poorly accessible forms of cancer. Recent advances in colloidal nanocrystal synthesis have led to the development of ultra-small crystals of gadolinium oxide (US-Gd(2)O(3), 2-3 nm diameter). As of today, this is the smallest and the densest of all Gd-containing nanoparticles. Cancer cells labeled with a sufficient quantity of this compound appear bright in T(1)-weighted MRI images. Here we demonstrate that US-Gd(2)O(3) can be used to label GL-261 glioblastoma multiforme cells, followed by localization and visualization in vivo using MRI. Very high amounts of Gd are efficiently internalized and retained in cells, as confirmed with TEM and ICP-MS. Labeled cells were visualized in vivo at 1.5 T using the chicken embryo model. This is one more step toward the development of "positively contrasted" cell tracking procedures with MRI.

  8. Refinement of Optical Imaging Spectroscopy Algorithms using concurrent BOLD and CBV fMRI

    PubMed Central

    Kennerley, Aneurin J; Berwick, Jason; Martindale, John; Johnston, David; Zheng, Ying; Mayhew, John E

    2009-01-01

    We describe the use of the three dimensional characteristics of the functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) and cerebral blood volume (CBV) MRI signal changes to refine a two dimensional optical imaging spectroscopy (OIS) algorithm. The cortical depth profiles of the BOLD and CBV changes following neural activation were used to parameterise a 5-layer heterogeneous tissue model used in the Monte Carlo simulations (MCS) of light transport through tissue in the OIS analysis algorithm. To transform the fMRI BOLD and CBV measurements into deoxy-haemoglobin (Hbr) profiles we inverted an MCS of extravascular MR signal attenuation under the assumption that the extra-/intravascular ratio is 2:1 at a magnetic field strength of 3T. The significant improvement in the quantitative accuracy of haemodynamic measurements using the new heterogeneous tissue model over the original homogeneous tissue model OIS algorithm was demonstrated on new concurrent OIS and fMRI data covering a range of stimulus durations. PMID:19505581

  9. Ferumoxytol-enhanced MRI to Image Inflammation within Human Brain Arteriovenous Malformations: A Pilot Investigation.

    PubMed

    Hasan, David M; Amans, Matthew; Tihan, Tarik; Hess, Christopher; Guo, Yi; Cha, Soonmee; Su, Hua; Martin, Alastair J; Lawton, Michael T; Neuwelt, Edward A; Saloner, David A; Young, William L

    2012-07-01

    Inflammation cell infiltration and cytokine expression are seen in the vascular walls and intervening stroma of resected brain arteriovenous malformation (bAVM) specimens, even in unruptured and previously untreated lesions. Macrophages may play a critical role in bAVM progression to rupture, and could serve as a marker for rupture risk. We assessed feasibility of imaging macrophages within the bAVM nidus using ferumoxytol-enhanced MRI in four patients with already diagnosed bAVMs using iron-sensitive imaging (ISI; T2*-GE-MRI sequence). Patients were imaged at baseline and at either 1 day (n=2) or 5 days (n=2) after infusion of 5mg/kg of ferumoxytol. Residual intravascular ferumoxytol obscured evaluation for uptake in bAVM vascular walls and stroma at the 1-day time point. The two cases imaged at 5 days showed less intravascular tracer but had signal loss in the nidal region consistent with ferumoxytol localization. One case underwent surgical resection; there was prominent vascular wall CD68 staining. Ferumoxytol-enhanced-MRI for assessing bAVM inflammatory cell burden appears feasible and has the potential to be developed as a biomarker to study lesional inflammatory events. PMID:23002401

  10. Tyrosinase as a multifunctional reporter gene for Photoacoustic/MRI/PET triple modality molecular imaging

    PubMed Central

    Qin, Chunxia; Cheng, Kai; Chen, Kai; Hu, Xiang; Liu, Yang; Lan, Xiaoli; Zhang, Yongxue; Liu, Hongguang; Xu, Yingding; Bu, Lihong; Su, Xinhui; Zhu, Xiaohua; Meng, Shuxian; Cheng, Zhen

    2013-01-01

    Development of reporter genes for multimodality molecular imaging is highly important. In contrast to the conventional strategies which have focused on fusing several reporter genes together to serve as multimodal reporters, human tyrosinase (TYR) – the key enzyme in melanin production – was evaluated in this study as a stand-alone reporter gene for in vitro and in vivo photoacoustic imaging (PAI), magnetic resonance imaging (MRI) and positron emission tomography (PET). Human breast cancer cells MCF-7 transfected with a plasmid that encodes TYR (named as MCF-7-TYR) and non-transfected MCF-7 cells were used as positive and negative controls, respectively. Melanin targeted N-(2-(diethylamino)ethyl)-18F-5-fluoropicolinamide was used as a PET reporter probe. In vivo PAI/MRI/PET imaging studies showed that MCF-7-TYR tumors achieved significant higher signals and tumor-to-background contrasts than those of MCF-7 tumor. Our study demonstrates that TYR gene can be utilized as a multifunctional reporter gene for PAI/MRI/PET both in vitro and in vivo. PMID:23508226

  11. Ferumoxytol-enhanced MRI to Image Inflammation within Human Brain Arteriovenous Malformations: A Pilot Investigation

    PubMed Central

    Hasan, David M.; Amans, Matthew; Tihan, Tarik; Hess, Christopher; Guo, Yi; Cha, Soonmee; Su, Hua; Martin, Alastair J.; Lawton, Michael T.; Neuwelt, Edward A.; Saloner, David A.; Young, William L.

    2012-01-01

    Inflammation cell infiltration and cytokine expression are seen in the vascular walls and intervening stroma of resected brain arteriovenous malformation (bAVM) specimens, even in unruptured and previously untreated lesions. Macrophages may play a critical role in bAVM progression to rupture, and could serve as a marker for rupture risk. We assessed feasibility of imaging macrophages within the bAVM nidus using ferumoxytol-enhanced MRI in four patients with already diagnosed bAVMs using iron-sensitive imaging (ISI; T2*-GE-MRI sequence). Patients were imaged at baseline and at either 1 day (n=2) or 5 days (n=2) after infusion of 5mg/kg of ferumoxytol. Residual intravascular ferumoxytol obscured evaluation for uptake in bAVM vascular walls and stroma at the 1-day time point. The two cases imaged at 5 days showed less intravascular tracer but had signal loss in the nidal region consistent with ferumoxytol localization. One case underwent surgical resection; there was prominent vascular wall CD68 staining. Ferumoxytol-enhanced-MRI for assessing bAVM inflammatory cell burden appears feasible and has the potential to be developed as a biomarker to study lesional inflammatory events. PMID:23002401

  12. 2D Imaging in a Lightweight Portable MRI Scanner without Gradient Coils

    PubMed Central

    Cooley, Clarissa Zimmerman; Stockmann, Jason P.; Armstrong, Brandon D.; Sarracanie, Mathieu; Lev, Michael H.; Rosen, Matthew S.; Wald, Lawrence L.

    2014-01-01

    Purpose As the premiere modality for brain imaging, MRI could find wider applicability if lightweight, portable systems were available for siting in unconventional locations such as Intensive Care Units, physician offices, surgical suites, ambulances, emergency rooms, sports facilities, or rural healthcare sites. Methods We construct and validate a truly portable (<100kg) and silent proof-of-concept MRI scanner which replaces conventional gradient encoding with a rotating lightweight cryogen-free, low-field magnet. When rotated about the object, the inhomogeneous field pattern is used as a rotating Spatial Encoding Magnetic field (rSEM) to create generalized projections which encode the iteratively reconstructed 2D image. Multiple receive channels are used to disambiguate the non-bijective encoding field. Results The system is validated with experimental images of 2D test phantoms. Similar to other non-linear field encoding schemes, the spatial resolution is position dependent with blurring in the center, but is shown to be likely sufficient for many medical applications. Conclusion The presented MRI scanner demonstrates the potential for portability by simultaneously relaxing the magnet homogeneity criteria and eliminating the gradient coil. This new architecture and encoding scheme shows convincing proof of concept images that are expected to be further improved with refinement of the calibration and methodology. PMID:24668520

  13. Clinical cell therapy imaging using a perfluorocarbon tracer and fluorine-19 MRI

    PubMed Central

    Ahrens, Eric T; Helfer, Brooke M; O'Hanlon, Charles F; Schirda, Claudiu

    2014-01-01

    Purpose Cellular therapeutics are emerging as a treatment option for a host of serious human diseases. To accelerate clinical translation, noninvasive imaging of cell grafts in clinical trials can potentially be used to assess the initial delivery and behavior of cells. Methods The use of a perfluorocarbon (PFC) tracer agent for clinical fluorine-19 (19F) MRI cell detection is described. This technology was used to detect immunotherapeutic dendritic cells (DCs) delivered to colorectal adenocarcinoma patients. Autologous DC vaccines were labeled with a PFC MRI agent ex vivo. Patients received DCs intradermally, and 19F spin-density-weighted MRI at 3 Tesla (T) was used to observe cells. Results Spin-density-weighted 19F images at the injection site displayed DCs as background-free “hot-spot” images. 19F images were acquired in clinically relevant scan times (<10 min). Apparent DC numbers could be quantified in two patients from the 19F hot-spots and were observed to decrease by ∼50% at injection site by 24 h. From 3T phantom studies, the sensitivity limit for DC detection is estimated to be on the order of ∼105 cells/voxel in this study. Conclusion These results help to establish a clinically applicable means to track a broad range of cell types used in cell therapy. Magn Reson Med 72:1696–1701, 2014. © 2014 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance. PMID:25241945

  14. Evaluation of congenital heart disease by cine magnetic resonance imaging (MRI)

    SciTech Connect

    Feiglin, D.H.I.; Moodie, D.S.; O'Donnell, J.K.; Go, R.T.; Sterba, R.; MacIntyre, W.J.

    1985-05-01

    The authors studied 11 adult patients (pts) with atrial septal defect (ASD) and 4 adult pts with ventricular septal defect (VSD) using cine magnetic resonance. All studies were performed using a .6T superconducting magnet with ECG gating and electronic axial rotation when appropriate. Repeated multislice image with no change in physiologic delay of the spin echo pulse sequence, but varying the time by offsetting one slice at each imaging stage allowed for an N x N collection of data where N is the number of slices in one collection set and is equal to the number of sets collected. Algebraic manipulation of the T1 weighted images (TE=30mSec TRimaging of the atrial septum than does conventional MRI. Using this technique, the authors have identified both atrial and ventricular septal defects in all pts preoperatively and have noted an intact atrial septum following surgery. Standard MRI produced 4 false positive studies postoperatively because only 1 phase of the cardiac cycle was reviewed. Cine MRI allows better identification of septal defects than standard static acquisitions. The cine technique also provides better definition and delineation of right sided abnormalities which are maximized when viewed in a cardiac major axis obtained by electronic axial rotation.

  15. Brain MRI Tumor Detection using Active Contour Model and Local Image Fitting Energy

    NASA Astrophysics Data System (ADS)

    Nabizadeh, Nooshin; John, Nigel

    2014-03-01

    Automatic abnormality detection in Magnetic Resonance Imaging (MRI) is an important issue in many diagnostic and therapeutic applications. Here an automatic brain tumor detection method is introduced that uses T1-weighted images and K. Zhang et. al.'s active contour model driven by local image fitting (LIF) energy. Local image fitting energy obtains the local image information, which enables the algorithm to segment images with intensity inhomogeneities. Advantage of this method is that the LIF energy functional has less computational complexity than the local binary fitting (LBF) energy functional; moreover, it maintains the sub-pixel accuracy and boundary regularization properties. In Zhang's algorithm, a new level set method based on Gaussian filtering is used to implement the variational formulation, which is not only vigorous to prevent the energy functional from being trapped into local minimum, but also effective in keeping the level set function regular. Experiments show that the proposed method achieves high accuracy brain tumor segmentation results.

  16. Model for B1 Imaging in MRI Using the Rotating RF Field

    PubMed Central

    Weber, Ewald; Crozier, Stuart

    2014-01-01

    Conventionally, magnetic resonance imaging (MRI) is performed by pulsing gradient coils, which invariably leads to strong acoustic noise, patient safety concerns due to induced currents, and costly power/space requirements. This modeling study investigates a new silent, gradient coil-free MR imaging method, in which a radiofrequency (RF) coil and its nonuniform field (B 1 +) are mechanically rotated about the patient. The advantage of the rotating B 1 + field is that, for the first time, it provides a large number of degrees of freedom to aid a successful B 1 + image encoding process. The mathematical modeling was performed using flip angle modulation as part of a finite-difference-based Bloch equation solver. Preliminary results suggest that representative MR images with intensity deviations of <5% from the original image can be obtained using rotating RF field approach. This method may open up new avenues towards anatomical and functional imaging in medicine. PMID:24963336

  17. Multimodality Functional Imaging in Radiation Therapy Planning: Relationships between Dynamic Contrast-Enhanced MRI, Diffusion-Weighted MRI, and 18F-FDG PET

    PubMed Central

    Mera Iglesias, Moisés; Aramburu Núñez, David; del Olmo Claudio, José Luis; Salvador Gómez, Francisco; Driscoll, Brandon; Coolens, Catherine; Alba Castro, José L.; Muñoz, Victor

    2015-01-01

    Objectives. Biologically guided radiotherapy needs an understanding of how different functional imaging techniques interact and link together. We analyse three functional imaging techniques that can be useful tools for achieving this objective. Materials and Methods. The three different imaging modalities from one selected patient are ADC maps, DCE-MRI, and 18F-FDG PET/CT, because they are widely used and give a great amount of complementary information. We show the relationship between these three datasets and evaluate them as markers for tumour response or hypoxia marker. Thus, vascularization measured using DCE-MRI parameters can determine tumour hypoxia, and ADC maps can be used for evaluating tumour response. Results. ADC and DCE-MRI include information from 18F-FDG, as glucose metabolism is associated with hypoxia and tumour cell density, although 18F-FDG includes more information about the malignancy of the tumour. The main disadvantage of ADC maps is the distortion, and we used only low distorted regions, and extracellular volume calculated from DCE-MRI can be considered equivalent to ADC in well-vascularized areas. Conclusion. A dataset for achieving the biologically guided radiotherapy must include a tumour density study and a hypoxia marker. This information can be achieved using only MRI data or only PET/CT studies or mixing both datasets. PMID:25788972

  18. Assessment of bias for MRI diffusion tensor imaging using SIMEX.

    PubMed

    Lauzon, Carolyn B; Asman, Andrew J; Crainiceanu, Ciprian; Caffo, Brian C; Landman, Bennett A

    2011-01-01

    Diffusion Tensor Imaging (DTI) is a Magnetic Resonance Imaging method for measuring water diffusion in vivo. One powerful DTI contrast is fractional anisotropy (FA). FA reflects the strength of water's diffusion directional preference and is a primary metric for neuronal fiber tracking. As with other DTI contrasts, FA measurements are obscured by the well established presence of bias. DTI bias has been challenging to assess because it is a multivariable problem including SNR, six tensor parameters, and the DTI collection and processing method used. SIMEX is a modem statistical technique that estimates bias by tracking measurement error as a function of added noise. Here, we use SIMEX to assess bias in FA measurements and show the method provides; i) accurate FA bias estimates, ii) representation of FA bias that is data set specific and accessible to non-statisticians, and iii) a first time possibility for incorporation of bias into DTI data analysis. PMID:21995019

  19. Three-dimensional correlation of MR images to muscle tissue response for interventional MRI thermal ablation

    NASA Astrophysics Data System (ADS)

    Breen, Michael S.; Lazebnik, Roee S.; Lewin, Jonathan S.; Wilson, David L.

    2003-05-01

    Solid tumors and other pathologies are being treated using radio-frequency (RF) ablation under interventional magnetic resonance imaging (iMRI) guidance. In animal experiments, we are investigating the ability of MR to monitor ablation treatments by comparing MR images of thermal lesions to histologically assayed cellular damage. We developed a new methodology using three-dimensional registration for making spatial correlations. A low-field, open MRI system was used to guide an ablation probe into the thigh muscle of 10 rabbits and acquire MR volumes post ablation. After the in vivo MR and histology images were aligned with a registration accuracy of 1.32 +/- 0.39 mm (mean +/- SD), a boundary of necrosis identified in histology images was compared with manually segmented boundaries of the elliptical hyperintense region in MR images. For 14 MR images, we determined that the outer boundary of the hyperintense region in MR closely corresponds to the region of cell death, with a mean absolute distance between boundaries of 0.97 mm. Since this distance may be less than our ability to measure such differences, boundaries may match perfectly. This is good evidence that MR lesion images can localize the region of cell death during RF ablation treatments.

  20. Molecular imaging of atherosclerosis with nanoparticle-based fluorinated MRI contrast agents

    PubMed Central

    Palekar, Rohun U; Jallouk, Andrew P; Lanza, Gregory M; Pan, Hua; Wickline, Samuel A

    2015-01-01

    As atherosclerosis remains one of the most prevalent causes of patient mortality, the ability to diagnose early signs of plaque rupture and thrombosis represents a significant clinical need. With recent advances in nanotechnology, it is now possible to image specific molecular processes noninvasively with MRI, using various types of nanoparticles as contrast agents. In the context of cardiovascular disease, it is possible to specifically deliver contrast agents to an epitope of interest for detecting vascular inflammatory processes, which serve as predecessors to atherosclerotic plaque development. Herein, we review various applications of nanotechnology in detecting atherosclerosis using MRI, with an emphasis on perfluorocarbon nanoparticles and fluorine imaging, along with theranostic prospects of nanotechnology in cardiovascular disease. PMID:26080701

  1. Automatic localization of the left ventricle in cardiac MRI images using deep learning.

    PubMed

    Emad, Omar; Yassine, Inas A; Fahmy, Ahmed S

    2015-08-01

    Automatic localization of the left ventricle (LV) in cardiac MRI images is an essential step for automatic segmentation, functional analysis, and content based retrieval of cardiac images. In this paper, we introduce a new approach based on deep Convolutional Neural Network (CNN) to localize the LV in cardiac MRI in short axis views. A six-layer CNN with different kernel sizes was employed for feature extraction, followed by Softmax fully connected layer for classification. The pyramids of scales analysis was introduced in order to take account of the different sizes of the heart. A publically-available database of 33 patients was used for learning and testing. The proposed method was able it localize the LV with 98.66%, 83.91% and 99.07% for accuracy, sensitivity and specificity respectively. PMID:26736354

  2. Integrating carthage-specific T1rho MRI into knee clinic diagnostic imaging.

    PubMed

    Pedersen, Douglas R; Klocke, Noelle F; Thedens, Daniel R; Martin, James A; Williams, Glenn N; Amendola, Annunziato

    2011-01-01

    With a rise in post-traumatic osteoarthritis, OA no longer is considered just a disease of aging. The 'gold standard' for OA diagnosis has long been planar radiographs for visualizing osteophytes, joint space narrowing and sclerotic changes. A typical magnetic resonance imaging (MRI) protocol will acquire proton density, T1, T2, and fat suppressed images that give a comprehensive picture of morphologic changes associated with injury and subsequent degenerative processes. However, the earliest events of cartilage degeneration occur within the tissue, before measureable changes in morphology. MRI methods have been proposed to display and quantify changes in composition and integrity of such elements of cartilage extracellular matrix as collagen and proteoglycan (PG) content in vivo. T1ρ the spin-lattice relaxation time in the rotating frame, has come to the forefront for visualizing water proton-PG interactions in articular cartilage. The purpose of this T1ρ MRI study was to define an objective femoral condyle-specific registration method, in which zone-dependent cartilage compositional changes could be assessed from the bone outward through the existing cartilage, at pre-ACL reconstruction and subsequent follow-up times, when the loss of thickness to surface-down cartilage erosion might occur later in the OA pathogenesis. Additionally, this study explores the effects of reducing the number of spin-lock times on the absolute T1ρ relaxation times; a major parameter in expanding T1ρ coverage to the whole joint while satisfying clinical imaging time and specific absorption rate (SAR) safety constraints. The developed image analysis tools serve as the first step toward quantitative functional assessment of cartilage health with noninvasive T1ρ MRI, which has the potential to become an important new tool for the early diagnosis of cartilage degeneration following ACL trauma.

  3. Robust segmentation of 4D cardiac MRI-tagged images via spatio-temporal propagation

    NASA Astrophysics Data System (ADS)

    Qian, Zhen; Huang, Xiaolei; Metaxas, Dimitris N.; Axel, Leon

    2005-04-01

    In this paper we present a robust method for segmenting and tracking cardiac contours and tags in 4D cardiac MRI tagged images via spatio-temporal propagation. Our method is based on two main techniques: the Metamorphs Segmentation for robust boundary estimation, and the tunable Gabor filter bank for tagging lines enhancement, removal and myocardium tracking. We have developed a prototype system based on the integration of these two techniques, and achieved efficient, robust segmentation and tracking with minimal human interaction.

  4. 3D segmentation of masses in DCE-MRI images using FCM and adaptive MRF

    NASA Astrophysics Data System (ADS)

    Zhang, Chengjie; Li, Lihua

    2014-03-01

    Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a sensitive imaging modality for the detection of breast cancer. Automated segmentation of breast lesions in DCE-MRI images is challenging due to inherent signal-to-noise ratios and high inter-patient variability. A novel 3D segmentation method based on FCM and MRF is proposed in this study. In this method, a MRI image is segmented by spatial FCM, firstly. And then MRF segmentation is conducted to refine the result. We combined with the 3D information of lesion in the MRF segmentation process by using segmentation result of contiguous slices to constraint the slice segmentation. At the same time, a membership matrix of FCM segmentation result is used for adaptive adjustment of Markov parameters in MRF segmentation process. The proposed method was applied for lesion segmentation on 145 breast DCE-MRI examinations (86 malignant and 59 benign cases). An evaluation of segmentation was taken using the traditional overlap rate method between the segmented region and hand-drawing ground truth. The average overlap rates for benign and malignant lesions are 0.764 and 0.755 respectively. Then we extracted five features based on the segmentation region, and used an artificial neural network (ANN) to classify between malignant and benign cases. The ANN had a classification performance measured by the area under the ROC curve of AUC=0.73. The positive and negative predictive values were 0.86 and 0.58, respectively. The results demonstrate the proposed method not only achieves a better segmentation performance in accuracy also has a reasonable classification performance.

  5. Recent advances in MRI technology: Implications for image quality and patient safety

    PubMed Central

    Sobol, Wlad T.

    2012-01-01

    Recent advances in MRI technology are presented, with emphasis on how this new technology impacts clinical operations (better image quality, faster exam times, and improved throughput). In addition, implications for patient safety are discussed with emphasis on the risk of patient injury due to either high local specific absorption rate (SAR) or large cumulative energy doses delivered during long exam times. Patient comfort issues are examined as well. PMID:23961024

  6. Magnetic Resonance Imaging (MRI) Evaluation of Perianal Fistulae with Surgical Correlation

    PubMed Central

    Singh, Navdeep; Thukral, CL; Singh, Kunwar Pal; Bhalla, Varun

    2014-01-01

    Aims: The purpose of the study was to evaluate the role of Magnetic Resonance Imaging in detection and characterization of perianal fistulae and correlating it with surgical findings. Methods: Fifty consecutive patients with suspected perianal fistulae having one or more external openings were prospectively selected for MRI evaluation. Previously operated or patients with recurrent perianal disease were excluded from the study. MRI findings were recorded according to “St. James’s University Hospital MR Imaging Classification of Perianal Fistulae” and correlated with surgical observations. Finally, comparison between T2-weighted fat saturated and postcontrast T1-weighted fat saturated sequences was done. Results: Amongst the total of 50 patients, per-operative findings confirmed perianal fistulae in 45 patients. The sensitivity and specificity of MRI in correctly detecting and grading the primary tract was found to be 95.56% and 80% respectively; for abscess, it was 87.50% and 95.24% respectively. High sensitivity was also discerned in identification of secondary tract (93.75%), correct localization of internal opening (95.83%) and for correctly detecting the horse-shoeing (87.50%). Our assumption of null hypothesis was accepted on comparing results of T2-weighted fat saturated sequences and postcontrast T1-weighted fat saturated sequences. Conclusion: Magnetic Resonance Imaging (MRI) was highly accurate in assessment of surgically important parameters (primary tract and its grading, internal opening, secondary tract, abscess, horseshoeing) of perianal fistulae. Comparison of results of imaging findings on T2-weighted and postcontrast T1-weighted fat saturated sequences were statistically similar, so contrast study can be omitted, particularly while evaluating primary / previously unoperated perianal fistulae. PMID:25121040

  7. Independent component analysis applied to pharmacological magnetic resonance imaging (phMRI): new insights into the functional networks underlying panic attacks as induced by CCK-4.

    PubMed

    Dieler, A C; Sämann, P G; Leicht, G; Eser, D; Kirsch, V; Baghai, T C; Karch, S; Schüle, C; Pogarell, O; Czisch, M; Rupprecht, R; Mulert, C

    2008-01-01

    Pharmacological magnetic resonance imaging (phMRI) is a method to study effects of psychopharmacological agents on neural activation. Changes of the blood oxygen level dependent (BOLD), the basis of functional MRI (fMRI), are typically obtained at relatively high sampling frequencies. This has more recently been exploited in the field of fMRI by applying independent component analysis (ICA), an explorative data analysis method decomposing activation into distinct neural networks. While already successfully used to investigate resting network and task-induced activity, its use in phMRI is new. Further extension of this method to tensorial probabilistic ICA (tensor PICA) allows to group similar brain activation across the anatomical, temporal, subject or session domain. This approach is useful for pharmacological experiments when no pharmacokinetic model exists. We exemplify this method using data from a placebo-controlled cholecystokinine-4 (CCK-4) injection experiment performed on 16 neuropsychiatrically and medically healthy males (age 25.6 +/- 4.2 years). Tensor PICA identified strong increases in activity in 12 networks. Comparison with results gained from the standard approach (voxelwise regression analysis) revealed good reproduction of areas previously associated with CCK-4 action, such as the anterior cingulate, orbitofrontal cortex, cerebellum, temporolateral, left parietal and insular areas, striatum, and precuneus. Several other components such as the dorsal anterior cingulate and medial prefrontal cortex were identified, suggesting higher sensitivity of the method. Exploration of the time courses of each activated network revealed differences, that might be lost when a fixed time course is modeled, e. g. neuronal responses to an acoustic warning signal prior to injection. Comparison of placebo and CCK-4 runs further showed that a proportion of networks are newly elicited by CCK-4 whereas other components are significantly active in the placebo conditions

  8. MRI of trabecular bone using a DDIF contrast imaging sequence

    PubMed Central

    Mintzopoulos, Dionyssios; Ackerman, Jerome L.; Song, Yi-Qiao

    2011-01-01

    Purpose To characterize the DDIF (Decay due to Diffusion in the Internal Field) method using intact animal trabecular bone specimens of varying trabecular structure and porosity, under ex vivo conditions closely resembling in vivo physiological conditions. The DDIF method provides a diffusion contrast which is related to the surface-to-volume ratio of the porous structure of bones. DDIF has previously been used successfully to study marrow-free trabecular bone, but the DDIF contrast hitherto had not been tested in intact specimens containing marrow and surrounded by soft tissue. Materials and Methods DDIF imaging was implemented on a 4.7 T small-bore, horizontal, animal scanner. Ex vivo results on fresh bone specimens containing marrow were obtained at body temperature. Control measurements were carried out in surrounding tissue and saline. Results Significant DDIF effect was observed for trabecular bone samples, while it was considerably smaller for soft tissue outside the bone and for lipids. Additionally, significant differences were observed between specimens of different trabecular structure. Conclusion The DDIF contrast is feasible despite the reduction of the diffusion constant and of T1 in such conditions, increasing our confidence that DDIF imaging in vivo may be clinically viable for bone characterization. PMID:21780229

  9. Is your system calibrated? MRI gradient system calibration for pre-clinical, high-resolution imaging.

    PubMed

    O'Callaghan, James; Wells, Jack; Richardson, Simon; Holmes, Holly; Yu, Yichao; Walker-Samuel, Simon; Siow, Bernard; Lythgoe, Mark F

    2014-01-01

    High-field, pre-clinical MRI systems are widely used to characterise tissue structure and volume in small animals, using high resolution imaging. Both applications rely heavily on the consistent, accurate calibration of imaging gradients, yet such calibrations are typically only performed during maintenance sessions by equipment manufacturers, and potentially with acceptance limits that are inadequate for phenotyping. To overcome this difficulty, we present a protocol for gradient calibration quality assurance testing, based on a 3D-printed, open source, structural phantom that can be customised to the dimensions of individual scanners and RF coils. In trials on a 9.4 T system, the gradient scaling errors were reduced by an order of magnitude, and displacements of greater than 100 µm, caused by gradient non-linearity, were corrected using a post-processing technique. The step-by-step protocol can be integrated into routine pre-clinical MRI quality assurance to measure and correct for these errors. We suggest that this type of quality assurance is essential for robust pre-clinical MRI experiments that rely on accurate imaging gradients, including small animal phenotyping and diffusion MR.

  10. Development of Laser-Polarized Noble Gas Magnetic Resonance Imaging (MRI) Technology

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2004-01-01

    We are developing technology for laser-polarized noble gas nuclear magnetic resonance (NMR), with the aim of enabling it as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation, perfusion, and gas-exchange. In addition, laser-polarized noble gases (3He and 1BXe) do not require a large magnetic field for sensitive NMR detection, opening the door to practical MRI with novel, open-access magnet designs at very low magnetic fields (and hence in confined spaces). We are pursuing two specific aims in this technology development program. The first aim is to develop an open-access, low-field (less than 0.01 T) instrument for MRI studies of human gas inhalation as a function of subject orientation, and the second aim is to develop functional imaging of the lung using laser-polarized He-3 and Xe-129.

  11. Magnetic Resonance Imaging (MRI) of PEM Dehydration and Gas Manifold Flooding During Continuous Fuel Cell Operation

    SciTech Connect

    Minard, Kevin R.; Vishwanathan, Vilanyur V.; Majors, Paul D.; Wang, Li Q.; Rieke, Peter C.

    2006-10-27

    The methods, apparatus, and results are reported for in-situ, near real time, magnetic resonance imaging (MRI) of MEA dehydration and gas manifold flooding in an operating PEM fuel cell. To acquire high-resolution, artifact-free images for visualizing water distribution, acquisition parameters for a standard, two-dimensional (2D), spin-echo sequence were first optimized for the measured magnetic field heterogeneity induced by fuel cell components. 2D images of water inside the fuel cell were then acquired every 128 seconds during 11.4 hours of continuous operation under constant load. Collected images revealed that MEA dehydration proceeded non-uniformly across its plane, starting from gas inlets and ending at gas outlets, and that upon completion of this dehydration process manifold flooding began. To understand these observations, acquired images were correlated to the current output and operating characteristics of the fuel cell. Results demonstrate the power of MRI for in-situ, near real-time imaging of water distribution and non-uniformity in operating PEM fuel cells, and highlight its utility for understanding PEM fuel cell operation, the causes of cell failure, and for developing new strategies of water management.

  12. Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET–MRI-guided radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

    2016-09-01

    Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  ‑1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  ‑19.9  ±  11.8% and  ‑8.1  ±  8.2% achieved by MRI segmentation-based (water

  13. Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning.

    PubMed

    Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

    2016-09-01

    Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  -1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  -19.9  ±  11.8% and  -8.1  ±  8.2% achieved by MRI segmentation-based (water

  14. Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

    2016-09-01

    Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  -1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  -19.9  ±  11.8% and  -8.1  ±  8.2% achieved by MRI segmentation-based (water

  15. Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning.

    PubMed

    Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

    2016-09-01

    Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  -1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  -19.9  ±  11.8% and  -8.1  ±  8.2% achieved by MRI segmentation-based (water

  16. Developing a quality control protocol for diffusion imaging on a clinical MRI system.

    PubMed

    Delakis, Ioannis; Moore, Elizabeth M; Leach, Martin O; De Wilde, Janet P

    2004-04-21

    This work describes the development of a quality control protocol, which can be implemented to assess the accuracy, precision and reproducibility of the apparent diffusion coefficient (ADC) measurement on a clinical magnetic resonance imaging (MRI) system. The precision and accuracy of the ADC measurement are analysed with regard to MRI system noise, signal reproducibility and differences between nominal and effective b values. Two aqueous test-solutions of CuSO4 and sucrose are prepared for the quality control protocol. ADC measurement with the CuSO4 solution is more sensitive to differences between nominal and effective b values, on account of the solution's high ADC. ADC measurement with the sucrose solution is more sensitive to signal reproducibility due to the solution's low baseline signal intensity. The ADC of the test-solutions is measured on an MRI system at our centre with a sequence used for clinical studies using diffusion imaging. Two parameters, Q and R, are defined for the analysis of the quality control ADC values. The Q parameter is the ratio of the standard deviation of the quality control mean ADC values over time to the optimal standard deviation, as derived from the effect of thermal noise on the ADC measurement uncertainty. Analysis with the Q parameter indicates that signal reproducibility errors contribute to ADC variations on our MRI system when imaging with high b values (b > 500 mm s(-2)), whereas differences between nominal and effective b values have a greater impact on the ADC measurement when imaging with low b values (b < 500 mm s(-2)). The R parameter is defined as the ratio of the directional variation of the ADC quality control values to the uncertainty of the ADC measurement. Analysis with the R parameter shows that the effect of directional variation of the ADC measurement on our MRI system is more pronounced when imaging with low b values. The quality control protocol identified a systematic error, which introduced a small

  17. IMaGe: Iterative Multilevel Probabilistic Graphical Model for Detection and Segmentation of Multiple Sclerosis Lesions in Brain MRI.

    PubMed

    Subbanna, Nagesh; Precup, Doina; Arnold, Douglas; Arbel, Tal

    2015-01-01

    In this paper, we present IMaGe, a new, iterative two-stage probabilistic graphical model for detection and segmentation of Multiple Sclerosis (MS) lesions. Our model includes two levels of Markov Random Fields (MRFs). At the bottom level, a regular grid voxel-based MRF identifies potential lesion voxels, as well as other tissue classes, using local and neighbourhood intensities and class priors. Contiguous voxels of a particular tissue type are grouped into regions. A higher, non-lattice MRF is then constructed, in which each node corresponds to a region, and edges are defined based on neighbourhood relationships between regions. The goal of this MRF is to evaluate the probability of candidate lesions, based on group intensity, texture and neighbouring regions. The inferred information is then propagated to the voxel-level MRF. This process of iterative inference between the two levels repeats as long as desired. The iterations suppress false positives and refine lesion boundaries. The framework is trained on 660 MRI volumes of MS patients enrolled in clinical trials from 174 different centres, and tested on a separate multi-centre clinical trial data set with 535 MRI volumes. All data consists of T1, T2, PD and FLAIR contrasts. In comparison to other MRF methods, such as, and a traditional MRF, IMaGe is much more sensitive (with slightly better PPV). It outperforms its nearest competitor by around 20% when detecting very small lesions (3-10 voxels). This is a significant result, as such lesions constitute around 40% of the total number of lesions. PMID:26221699

  18. Vision 20/20: Magnetic resonance imaging-guided attenuation correction in PET/MRI: Challenges, solutions, and opportunities.

    PubMed

    Mehranian, Abolfazl; Arabi, Hossein; Zaidi, Habib

    2016-03-01

    Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing novel strategies for deriving accurate attenuation maps with the aim to improve the quantitative accuracy of these emerging hybrid imaging systems. The attenuation map in PET/MRI should ideally be derived from anatomical MR images; however, MRI intensities reflect proton density and relaxation time properties of biological tissues rather than their electron density and photon attenuation properties. Therefore, in contrast to PET/computed tomography, there is a lack of standardized global mapping between the intensities of MRI signal and linear attenuation coefficients at 511 keV. Moreover, in standard MRI sequences, bones and lung tissues do not produce measurable signals owing to their low proton density and short transverse relaxation times. MR images are also inevitably subject to artifacts that degrade their quality, thus compromising their applicability for the task of attenuation correction in PET/MRI. MRI-guided attenuation correction strategies can be classified in three broad categories: (i) segmentation-based approaches, (ii) atlas-registration and machine learning methods, and (iii) emission/transmission-based approaches. This paper summarizes past and current state-of-the-art developments and latest advances in PET/MRI attenuation correction. The advantages and drawbacks of each approach for addressing the challenges of MR-based attenuation correction are comprehensively described. The opportunities brought by both MRI and PET imaging modalities for deriving accurate attenuation maps and improving PET quantification will be elaborated. Future prospects and potential clinical applications of these techniques and their integration in commercial

  19. Optical motion tracking to improve image quality in MRI of the brain

    NASA Astrophysics Data System (ADS)

    Maclaren, Julian; Aksoy, Murat; Ooi, Melvyn; Bammer, Roland

    2012-10-01

    Magnetic resonance imaging (MRI) of the brain is highly sensitivity to head motion. Prospective motion correction is a promising new method to prevent artifacts resulting from this effect. The image volume is continuously updated based on head tracking information, ensuring that the magnetic fields used for imaging maintain a constant geometric relationship relative to the object. This paper reviews current developments and methods of performing prospective correction. Optical tracking using cameras has major advantages over other methods used to obtain head pose information, as it does not affect the MR imaging process or interfere with the sequence timing. Results show that motion artifacts can be almost completely prevented for most imaging sequences. Despite this success, there are still engineering challenges to be solved before the technique becomes widely accepted in the clinic. These include improvements in miniaturization, marker fixation and MR compatibility.

  20. Magnetic Resonance Imaging (MRI) Evaluation of Developmental Delay in Pediatric Patients

    PubMed Central

    Syed, Naziya P.; Murthy, G.S.N.; Nori, Madhavi; Abkari, Anand; Pooja, B.K.; Venkateswarlu, J.

    2015-01-01

    Introduction: Developmental delay is defined as significant delay in one or more developmental domains. Magnetic Resonance Imaging (MRI) is the best modality to investigate such patients. Evaluation of a child with developmental delay is important not only because it allows early diagnosis and treatment but also helpful for parental counseling regarding the outcome of their child and to identify any possible risk of recurrence in the siblings. Thus this study was undertaken to evaluate the developmental delay in Indian children which will help the clinicians in providing an estimation of the child’s ultimate developmental potential and organize specific treatment requirement and also relieve parental apprehension. Aims and Objectives: To study the prevalence of normal and abnormal MRI in pediatric patients presenting with developmental delay and further categorize the abnormal MRI based on its morphological features. Materials and Methods: It is a prospective, observational & descriptive study of MRI Brain in 81 paediatric patients (46 Males and 35 Females), aged between three months to 12 years; presenting with developmental delay in Deccan College of Medical Sciences, Hyderabad; over a period of three years (Sept 2011 to Sept 2014). MRI brain was done on 1.5T Siemens Magnetom Essenza & 0.35T Magnetom C with appropriate sequences and planes after making the child sleep/sedated/ anesthetized. Various anatomical structures like Ventricles, Corpus callosum, etc were systematically assessed. The MRI findings were divided into various aetiological subgroups. Results: Normal MRI findings were seen in 32% cases and 68% had abnormal findings of which the proportion of Traumatic/ Neurovascular Diseases, Congenital & Developmental, Metabolic and Degenerative, neoplastic and non specific were 31%, 17%, 10%, 2.5% and 7.5% respectively. The ventricles and white matter mainly the corpus callosum were the most commonly affected anatomical structures. The diagnostic yield was

  1. Graph-based retrospective 4D image construction from free-breathing MRI slice acquisitions

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Ciesielski, Krzysztof C.; McDonough, Joseph M.; Mong, Andrew; Campbell, Robert M.

    2014-03-01

    4D or dynamic imaging of the thorax has many potential applications [1, 2]. CT and MRI offer sufficient speed to acquire motion information via 4D imaging. However they have different constraints and requirements. For both modalities both prospective and retrospective respiratory gating and tracking techniques have been developed [3, 4]. For pediatric imaging, x-ray radiation becomes a primary concern and MRI remains as the de facto choice. The pediatric subjects we deal with often suffer from extreme malformations of their chest wall, diaphragm, and/or spine, as such patient cooperation needed by some of the gating and tracking techniques are difficult to realize without causing patient discomfort. Moreover, we are interested in the mechanical function of their thorax in its natural form in tidal breathing. Therefore free-breathing MRI acquisition is the ideal modality of imaging for these patients. In our set up, for each coronal (or sagittal) slice position, slice images are acquired at a rate of about 200-300 ms/slice over several natural breathing cycles. This produces typically several thousands of slices which contain both the anatomic and dynamic information. However, it is not trivial to form a consistent and well defined 4D volume from these data. In this paper, we present a novel graph-based combinatorial optimization solution for constructing the best possible 4D scene from such data entirely in the digital domain. Our proposed method is purely image-based and does not need breath holding or any external surrogates or instruments to record respiratory motion or tidal volume. Both adult and children patients' data are used to illustrate the performance of the proposed method. Experimental results show that the reconstructed 4D scenes are smooth and consistent spatially and temporally, agreeing with known shape and motion of the lungs.

  2. Electrical source imaging of interictal spikes using multiple sparse volumetric priors for presurgical epileptogenic focus localization

    PubMed Central

    Strobbe, Gregor; Carrette, Evelien; López, José David; Montes Restrepo, Victoria; Van Roost, Dirk; Meurs, Alfred; Vonck, Kristl; Boon, Paul; Vandenberghe, Stefaan; van Mierlo, Pieter

    2016-01-01

    Electrical source imaging of interictal spikes observed in EEG recordings of patients with refractory epilepsy provides useful information to localize the epileptogenic focus during the presurgical evaluation. However, the selection of the time points or time epochs of the spikes in order to estimate the origin of the activity remains a challenge. In this study, we consider a Bayesian EEG source imaging technique for distributed sources, i.e. the multiple volumetric sparse priors (MSVP) approach. The approach allows to estimate the time courses of the intensity of the sources corresponding with a specific time epoch of the spike. Based on presurgical averaged interictal spikes in six patients who were successfully treated with surgery, we estimated the time courses of the source intensities for three different time epochs: (i) an epoch starting 50 ms before the spike peak and ending at 50% of the spike peak during the rising phase of the spike, (ii) an epoch starting 50 ms before the spike peak and ending at the spike peak and (iii) an epoch containing the full spike time period starting 50 ms before the spike peak and ending 230 ms after the spike peak. To identify the primary source of the spike activity, the source with the maximum energy from 50 ms before the spike peak till 50% of the spike peak was subsequently selected for each of the time windows. For comparison, the activity at the spike peaks and at 50% of the peaks was localized using the LORETA inversion technique and an ECD approach. Both patient-specific spherical forward models and patient-specific 5-layered finite difference models were considered to evaluate the influence of the forward model. Based on the resected zones in each of the patients, extracted from post-operative MR images, we compared the distances to the resection border of the estimated activity. Using the spherical models, the distances to the resection border for the MSVP approach and each of the different time epochs were in

  3. Electrical source imaging of interictal spikes using multiple sparse volumetric priors for presurgical epileptogenic focus localization.

    PubMed

    Strobbe, Gregor; Carrette, Evelien; López, José David; Montes Restrepo, Victoria; Van Roost, Dirk; Meurs, Alfred; Vonck, Kristl; Boon, Paul; Vandenberghe, Stefaan; van Mierlo, Pieter

    2016-01-01

    Electrical source imaging of interictal spikes observed in EEG recordings of patients with refractory epilepsy provides useful information to localize the epileptogenic focus during the presurgical evaluation. However, the selection of the time points or time epochs of the spikes in order to estimate the origin of the activity remains a challenge. In this study, we consider a Bayesian EEG source imaging technique for distributed sources, i.e. the multiple volumetric sparse priors (MSVP) approach. The approach allows to estimate the time courses of the intensity of the sources corresponding with a specific time epoch of the spike. Based on presurgical averaged interictal spikes in six patients who were successfully treated with surgery, we estimated the time courses of the source intensities for three different time epochs: (i) an epoch starting 50 ms before the spike peak and ending at 50% of the spike peak during the rising phase of the spike, (ii) an epoch starting 50 ms before the spike peak and ending at the spike peak and (iii) an epoch containing the full spike time period starting 50 ms before the spike peak and ending 230 ms after the spike peak. To identify the primary source of the spike activity, the source with the maximum energy from 50 ms before the spike peak till 50% of the spike peak was subsequently selected for each of the time windows. For comparison, the activity at the spike peaks and at 50% of the peaks was localized using the LORETA inversion technique and an ECD approach. Both patient-specific spherical forward models and patient-specific 5-layered finite difference models were considered to evaluate the influence of the forward model. Based on the resected zones in each of the patients, extracted from post-operative MR images, we compared the distances to the resection border of the estimated activity. Using the spherical models, the distances to the resection border for the MSVP approach and each of the different time epochs were in

  4. Iron-Loaded Magnetic Nanocapsules for pH-Triggered Drug Release and MRI Imaging

    PubMed Central

    2014-01-01

    Magnetic nanocapsules were synthesized for controlled drug release, magnetically assisted delivery, and MRI imaging. These magnetic nanocapsules, consisting of a stable iron nanocore and a mesoporous silica shell, were synthesized by controlled encapsulation of ellipsoidal hematite in silica, partial etching of the hematite core in acid, and reduction of the core by hydrogen. The iron core provided a high saturation magnetization and was stable against oxidation for at least 6 months in air and 1 month in aqueous solution. The hollow space between the iron core and mesoporous silica shell was used to load anticancer drug and a T1-weighted MRI contrast agent (Gd-DTPA). These multifunctional monodispersed magnetic “nanoeyes” were coated by multiple polyelectrolyte layers of biocompatible poly-l-lysine and sodium alginate to control the drug release as a function of pH. We studied pH-controlled release, magnetic hysteresis curves, and T1/T2 MRI contrast of the magnetic nanoeyes. They also served as MRI contrast agents with relaxivities of 8.6 mM–1 s–1 (r1) and 285 mM–1 s–1 (r2). PMID:24748722

  5. Synthesis of Gd2O3:Eu nanoplatelets for MRI and fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Maalej, Nabil M.; Qurashi, Ahsanulhaq; Assadi, Achraf Amir; Maalej, Ramzi; Shaikh, Mohammed Nasiruzzaman; Ilyas, Muhammad; Gondal, Mohammad A.

    2015-05-01

    We synthesized Gd2O3 and Gd2O3 doped by europium (Eu) (2% to 10%) nanoplatelets using the polyol chemical method. The synthesized nanoplatelets were characterized by X-ray diffraction (XRD), FESEM, TEM, and EDX techniques. The optical properties of the synthesized nanoplatelets were investigated by photoluminescence spectroscopy. We also studied the magnetic resonance imaging (MRI) contrast enhancement of T1 relaxivity using 3 T MRI. The XRD for Gd2O3 revealed a cubic crystalline structure. The XRD of Gd2O3:Eu3+ nanoplatelets were highly consistent with Gd2O3 indicating the total incorporation of the Eu3+ ions in the Gd2O3 matrix. The Eu doping of Gd2O3 produced red luminescence around 612 nm corresponding to the radiative transitions from the Eu-excited state 5D0 to the 7F2. The photoluminescence was maximal at 5% Eu doping concentration. The stimulated CIE chromaticity coordinates were also calculated. Judd-Ofelt analysis was used to obtain the radiative properties of the sample from the emission spectra. The MRI contrast enhancement due to Gd2O3 was compared to DOTAREM commercial contrast agent at similar concentration of gadolinium oxide and provided similar contrast enhancement. The incorporation of Eu, however, decreased the MRI contrast due to replacement of gadolinium by Eu.

  6. Synthesis of Gd2O3:Eu nanoplatelets for MRI and fluorescence imaging.

    PubMed

    Maalej, Nabil M; Qurashi, Ahsanulhaq; Assadi, Achraf Amir; Maalej, Ramzi; Shaikh, Mohammed Nasiruzzaman; Ilyas, Muhammad; Gondal, Mohammad A

    2015-01-01

    We synthesized Gd2O3 and Gd2O3 doped by europium (Eu) (2% to 10%) nanoplatelets using the polyol chemical method. The synthesized nanoplatelets were characterized by X-ray diffraction (XRD), FESEM, TEM, and EDX techniques. The optical properties of the synthesized nanoplatelets were investigated by photoluminescence spectroscopy. We also studied the magnetic resonance imaging (MRI) contrast enhancement of T1 relaxivity using 3 T MRI. The XRD for Gd2O3 revealed a cubic crystalline structure. The XRD of Gd2O3:Eu(3+) nanoplatelets were highly consistent with Gd2O3 indicating the total incorporation of the Eu(3+) ions in the Gd2O3 matrix. The Eu doping of Gd2O3 produced red luminescence around 612 nm corresponding to the radiative transitions from the Eu-excited state (5)D0 to the (7)F2. The photoluminescence was maximal at 5% Eu doping concentration. The stimulated CIE chromaticity coordinates were also calculated. Judd-Ofelt analysis was used to obtain the radiative properties of the sample from the emission spectra. The MRI contrast enhancement due to Gd2O3 was compared to DOTAREM commercial contrast agent at similar concentration of gadolinium oxide and provided similar contrast enhancement. The incorporation of Eu, however, decreased the MRI contrast due to replacement of gadolinium by Eu.

  7. Imaging performance of a hybrid x-ray computed tomography-fluorescence molecular tomography system using priors

    SciTech Connect

    Ale, Angelique; Schulz, Ralf B.; Sarantopoulos, Athanasios; Ntziachristos, Vasilis

    2010-05-15

    Purpose: The performance is studied of two newly introduced and previously suggested methods that incorporate priors into inversion schemes associated with data from a recently developed hybrid x-ray computed tomography and fluorescence molecular tomography system, the latter based on CCD camera photon detection. The unique data set studied attains accurately registered data of high spatially sampled photon fields propagating through tissue along 360 deg. projections. Methods: Approaches that incorporate structural prior information were included in the inverse problem by adding a penalty term to the minimization function utilized for image reconstructions. Results were compared as to their performance with simulated and experimental data from a lung inflammation animal model and against the inversions achieved when not using priors. Results: The importance of using priors over stand-alone inversions is also showcased with high spatial sampling simulated and experimental data. The approach of optimal performance in resolving fluorescent biodistribution in small animals is also discussed. Conclusions: Inclusion of prior information from x-ray CT data in the reconstruction of the fluorescence biodistribution leads to improved agreement between the reconstruction and validation images for both simulated and experimental data.

  8. Pelvis MRI scan

    MedlinePlus

    MRI - pelvis; MRI - hips; Pelvic MRI with prostate probe; Magnetic resonance imaging - pelvis ... care provider if you are afraid of close spaces (have claustrophobia). You may be given a medicine ...

  9. Breast MRI scan

    MedlinePlus

    MRI - breast; Magnetic resonance imaging - breast; Breast cancer - MRI; Breast cancer screening - MRI ... the same breast or the other breast after breast cancer has been diagnosed Distinguish between scar tissue and ...

  10. Automatic image-driven segmentation of cardiac ventricles in cine anatomical MRI

    NASA Astrophysics Data System (ADS)

    Cocosco, Chris A.; Niessen, Wiro J.; Netsch, Thomas; Vonken, Evert-jan P. A.; Viergever, Max A.

    2005-08-01

    The automatic segmentation of the heart's two ventricles from dynamic ("cine") cardiac anatomical images, such as 3D+time short-axis MRI, is of significant clinical importance. Previously published automated methods have various disadvantages for routine clinical use. This work reports about a novel automatic segmentation method that is very fast, and robust against anatomical variability and image contrast variations. The method is mostly image-driven: it fully exploits the information provided by modern 4D (3D+time) balanced Fast Field Echo (bFFE) cardiac anatomical MRI, and makes only few and plausible assumptions about the images and the imaged heart. Specifically, the method does not need any geometrical shape models nor complex gray-level appearance models. The method simply uses the two ventricles' contraction-expansion cycle, as well as the ventricles' spatial coherence along the time dimension. The performance of the cardiac ventricles segmentation method was demonstrated through a qualitative visual validation on 32 clinical exams: no gross failures for the left-ventricle (right-ventricle) on 32 (30) of the exams were found. Also, a clinical validation of resulting quantitative cardiac functional parameters was performed against a manual quantification of 18 exams; the automatically computed Ejection Fraction (EF) correlated well to the manually computed one: linear regression with RMS=3.7% (RMS expressed in EF units).

  11. Automated Robust Image Segmentation: Level Set Method Using Nonnegative Matrix Factorization with Application to Brain MRI.

    PubMed

    Dera, Dimah; Bouaynaya, Nidhal; Fathallah-Shaykh, Hassan M

    2016-07-01

    We address the problem of fully automated region discovery and robust image segmentation by devising a new deformable model based on the level set method (LSM) and the probabilistic nonnegative matrix factorization (NMF). We describe the use of NMF to calculate the number of distinct regions in the image and to derive the local distribution of the regions, which is incorporated into the energy functional of the LSM. The results demonstrate that our NMF-LSM method is superior to other approaches when applied to synthetic binary and gray-scale images and to clinical magnetic resonance images (MRI) of the human brain with and without a malignant brain tumor, glioblastoma multiforme. In particular, the NMF-LSM method is fully automated, highly accurate, less sensitive to the initial selection of the contour(s) or initial conditions, more robust to noise and model parameters, and able to detect as small distinct regions as desired. These advantages stem from the fact that the proposed method relies on histogram information instead of intensity values and does not introduce nuisance model parameters. These properties provide a general approach for automated robust region discovery and segmentation in heterogeneous images. Compared with the retrospective radiological diagnoses of two patients with non-enhancing grade 2 and 3 oligodendroglioma, the NMF-LSM detects earlier progression times and appears suitable for monitoring tumor response. The NMF-LSM method fills an important need of automated segmentation of clinical MRI. PMID:27417984

  12. An image acquisition and registration strategy for the fusion of hyperpolarized helium-3 MRI and x-ray CT images of the lung

    NASA Astrophysics Data System (ADS)

    Ireland, Rob H.; Woodhouse, Neil; Hoggard, Nigel; Swinscoe, James A.; Foran, Bernadette H.; Hatton, Matthew Q.; Wild, Jim M.

    2008-11-01

    The purpose of this ethics committee approved prospective study was to evaluate an image acquisition and registration protocol for hyperpolarized helium-3 magnetic resonance imaging (3He-MRI) and x-ray computed tomography. Nine patients with non-small cell lung cancer (NSCLC) gave written informed consent to undergo a free-breathing CT, an inspiration breath-hold CT and a 3D ventilation 3He-MRI in CT position using an elliptical birdcage radiofrequency (RF) body coil. 3He-MRI to CT image fusion was performed using a rigid registration algorithm which was assessed by two observers using anatomical landmarks and a percentage volume overlap coefficient. Registration of 3He-MRI to breath-hold CT was more accurate than to free-breathing CT; overlap 82.9 ± 4.2% versus 59.8 ± 9.0% (p < 0.001) and mean landmark error 0.75 ± 0.24 cm versus 1.25 ± 0.60 cm (p = 0.002). Image registration is significantly improved by using an imaging protocol that enables both 3He-MRI and CT to be acquired with similar breath holds and body position through the use of a birdcage 3He-MRI body RF coil and an inspiration breath-hold CT. Fusion of 3He-MRI to CT may be useful for the assessment of patients with lung diseases.

  13. Characterizing growth patterns in longitudinal MRI using image contrast

    NASA Astrophysics Data System (ADS)

    Vardhan, Avantika; Prastawa, Marcel; Vachet, Clement; Piven, Joseph; Gerig, Guido

    2014-03-01

    Understanding the growth patterns of the early brain is crucial to the study of neuro-development. In the early stages of brain growth, a rapid sequence of biophysical and chemical processes take place. A crucial component of these processes, known as myelination, consists of the formation of a myelin sheath around a nerve fiber, enabling the effective transmission of neural impulses. As the brain undergoes myelination, there is a subsequent change in the contrast between gray matter and white matter as observed in MR scans. In this work, gray-white matter contrast is proposed as an effective measure of appearance which is relatively invariant to location, scanner type, and scanning conditions. To validate this, contrast is computed over various cortical regions for an adult human phantom. MR (Magnetic Resonance) images of the phantom were repeatedly generated using different scanners, and at different locations. Contrast displays less variability over changing conditions of scan compared to intensity-based measures, demonstrating that it is less dependent than intensity on external factors. Additionally, contrast is used to analyze longitudinal MR scans of the early brain, belonging to healthy controls and Down's Syndrome (DS) patients. Kernel regression is used to model subject-specific trajectories of contrast changing with time. Trajectories of contrast changing with time, as well as time-based biomarkers extracted from contrast modeling, show large differences between groups. The preliminary applications of contrast based analysis indicate its future potential to reveal new information not covered by conventional volumetric or deformation-based analysis, particularly for distinguishing between normal and abnormal growth patterns.

  14. Functional imaging of murine hearts using accelerated self-gated UTE cine MRI.

    PubMed

    Motaal, Abdallah G; Noorman, Nils; de Graaf, Wolter L; Hoerr, Verena; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

    2015-01-01

    We introduce a fast protocol for ultra-short echo time (UTE) Cine magnetic resonance imaging (MRI) of the beating murine heart. The sequence involves a self-gated UTE with golden-angle radial acquisition and compressed sensing reconstruction. The self-gated acquisition is performed asynchronously with the heartbeat, resulting in a randomly undersampled kt-space that facilitates compressed sensing reconstruction. The sequence was tested in 4 healthy rats and 4 rats with chronic myocardial infarction, approximately 2 months after surgery. As a control, a non-accelerated self-gated multi-slice FLASH sequence with an echo time (TE) of 2.76 ms, 4.5 signal averages, a matrix of 192 × 192, and an acquisition time of 2 min 34 s per slice was used to obtain Cine MRI with 15 frames per heartbeat. Non-accelerated UTE MRI was performed with TE = 0.29 ms, a reconstruction matrix of 192 × 192, and an acquisition time of 3 min 47 s per slice for 3.5 averages. Accelerated imaging with 2×, 4× and 5× undersampled kt-space data was performed with 1 min, 30 and 15 s acquisitions, respectively. UTE Cine images up to 5× undersampled kt-space data could be successfully reconstructed using a compressed sensing algorithm. In contrast to the FLASH Cine images, flow artifacts in the UTE images were nearly absent due to the short echo time, simplifying segmentation of the left ventricular (LV) lumen. LV functional parameters derived from the control and the accelerated Cine movies were statistically identical.

  15. Masking level differences--a diffusion tensor imaging and functional MRI study.

    PubMed

    Wack, David S; Polak, Paul; Furuyama, Jon; Burkard, Robert F

    2014-01-01

    In our previous study we investigated Masking Level Differences (MLD) using functional Magnetic Resonance Imaging (fMRI), but were unable to confirm neural correlations for the MLD within the auditory cortex and inferior colliculus. Here we have duplicated conditions from our previous study, but have included more participants and changed the study site to a new location with a newer scanner and presentation system. Additionally, Diffusion Tensor Imaging (DTI) is included to allow investigation of fiber tracts that may be involved with MLDs. Twenty participants were included and underwent audiometric testing and MRI scanning. The current study revealed regions of increased and decreased activity within the auditory cortex when comparing the combined noise and signal of the dichotic MLD stimuli (N0Sπ and NπS0) with N0S0. Furthermore, we found evidence of inferior colliculus involvement. Our DTI findings show strong correlations between DTI measures within the brainstem and signal detection threshold levels. Patterns of correlation when the signal was presented only to the right ear showed an extensive network in the left hemisphere; however, the opposite was not true for the signal presented only to the left ear. Our current study was able to confirm what we had previously hypothesized using fMRI, while extending our investigation of MLDs to include the characteristics of connecting neural pathways. PMID:24558392

  16. Imaging the accumulation and suppression of tau pathology using multiparametric MRI

    PubMed Central

    Holmes, Holly E.; Colgan, Niall; Ismail, Ozama; Ma, Da; Powell, Nick M.; O'Callaghan, James M.; Harrison, Ian F.; Johnson, Ross A.; Murray, Tracey K.; Ahmed, Zeshan; Heggenes, Morton; Fisher, Alice; Cardoso, M.J.; Modat, Marc; Walker-Samuel, Simon; Fisher, Elizabeth M.C.; Ourselin, Sebastien; O'Neill, Michael J.; Wells, Jack A.; Collins, Emily C.; Lythgoe, Mark F.

    2016-01-01

    Mouse models of Alzheimer's disease have served as valuable tools for investigating pathogenic mechanisms relating to neurodegeneration, including tau-mediated and neurofibrillary tangle pathology—a major hallmark of the disease. In this work, we have used multiparametric magnetic resonance imaging (MRI) in a longitudinal study of neurodegeneration in the rTg4510 mouse model of tauopathy, a subset of which were treated with doxycycline at different time points to suppress the tau transgene. Using this paradigm, we investigated the sensitivity of multiparametric MRI to both the accumulation and suppression of pathologic tau. Tau-related atrophy was discernible from 5.5 months within the cortex and hippocampus. We observed markedly less atrophy in the treated rTg4510 mice, which was enhanced after doxycycline intervention from 3.5 months. We also observed differences in amide proton transfer, cerebral blood flow, and diffusion tensor imaging parameters in the rTg4510 mice, which were significantly less altered after doxycycline treatment. We propose that these non-invasive MRI techniques offer insight into pathologic mechanisms underpinning Alzheimer's disease that may be important when evaluating emerging therapeutics targeting one of more of these processes. PMID:26923415

  17. Microfluidic laminate-based phantom for diffusion tensor-magnetic resonance imaging (DT-MRI).

    PubMed

    Samuel, R; Sant, H J; Jiao, F; Johnson, C R; Gale, B K

    2011-09-01

    This paper reports fabrication of a magnetic resonance imaging (MRI) phantom created by stacking of multiple thin polydimethylsiloxane (PDMS) layers. PDMS is spin coated on SU-8 molds to obtain the desired layer thickness and imprints of the microchannel patterns that define the phantom geometry. This paper also identifies the unique challenges related to the fabrication and assembly of multiple thin layers and reports for the first time assembly of a large number of thin laminates of this nature. Use of photolithography techniques allows us to create a wide range of phantom geometries. The target dimensions of the phantoms reported here are (i) a stack of 30 thin PDMS layers of 10 µm thickness (ii) curved 5 µm × 5 µm microchannels with 8.7 µm spacing, and (iii) straight 5 µm × 5 µm microchannels with 3.6 µm spacing. SEM scans of the assembled phantoms show open microchannels and a monolithic cross-section with no visible interface between PDMS layers. Based on the results of diffusion tensor magnetic resonance imaging (DT-MRI) scan, the anisotropic diffusion of water molecules due to the physical restriction of the microchannels was detected, which means that the phantom can be used to calibrate and optimize MRI instrumentation. PMID:22865956

  18. MRI-guided fiber-based fluorescence molecular tomography for preclinical atherosclerosis imaging

    NASA Astrophysics Data System (ADS)

    Li, Baoqiang; Pouliot, Philippe; Lesage, Frederic

    2014-09-01

    Multi-modal imaging combining fluorescent molecular tomography (FMT) with MRI could provide information in these two modalities as well as optimize the recovery of functional information with MR-guidance. Here, we present a MRI-guided FMT system. An optical probe was designed consisting of a fiber plate on the top and bottom sides of the animal bed, respectively. In experiment, animal was installed between the two plates. Mounting fibers on each plate, transmission measuring could be conducted from both sides of the animal. Moreover, an accurate fluorescence reconstruction was achieved with MRI-derived anatomical guidance. The sensitivity of the FMT system was evaluated with a phantom showing that with long fibers, it was sufficient to detect 10nM Cy5.5 solution with ~28.5 dB in the phantom. The system was eventually used to image MMP activity involved in atherosclerosis with two ATX mice and two control mice. The reconstruction results were in agreement with ex vivo measurement.

  19. Computer-aided assessment of anomalies in the scoliotic spine in 3-D MRI images.

    PubMed

    Jäger, Florian; Hornegger, Joachim; Schwab, Siegfried; Janka, Rolf

    2009-01-01

    The assessment of anomalies in the scoliotic spine using Magnetic Resonance Imaging (MRI) is an essential task during the planning phase of a patient's treatment and operations. Due to the pathologic bending of the spine, this is an extremely time consuming process as an orthogonal view onto every vertebra is required. In this article we present a system for computer-aided assessment (CAA) of anomalies in 3-D MRI images of the spine relying on curved planar reformations (CPR). We introduce all necessary steps, from the pre-processing of the data to the visualization component. As the core part of the framework is based on a segmentation of the spinal cord we focus on this. The proposed segmentation method is an iterative process. In every iteration the segmentation is updated by an energy based scheme derived from Markov random field (MRF) theory. We evaluate the segmentation results on public available clinical relevant 3-D MRI data sets of scoliosis patients. In order to assess the quality of the segmentation we use the angle between automatically computed planes through the vertebra and planes estimated by medical experts. This results in a mean angle difference of less than six degrees.

  20. Imaging the accumulation and suppression of tau pathology using multiparametric MRI.

    PubMed

    Holmes, Holly E; Colgan, Niall; Ismail, Ozama; Ma, Da; Powell, Nick M; O'Callaghan, James M; Harrison, Ian F; Johnson, Ross A; Murray, Tracey K; Ahmed, Zeshan; Heggenes, Morton; Fisher, Alice; Cardoso, M J; Modat, Marc; Walker-Samuel, Simon; Fisher, Elizabeth M C; Ourselin, Sebastien; O'Neill, Michael J; Wells, Jack A; Collins, Emily C; Lythgoe, Mark F

    2016-03-01

    Mouse models of Alzheimer's disease have served as valuable tools for investigating pathogenic mechanisms relating to neurodegeneration, including tau-mediated and neurofibrillary tangle pathology-a major hallmark of the disease. In this work, we have used multiparametric magnetic resonance imaging (MRI) in a longitudinal study of neurodegeneration in the rTg4510 mouse model of tauopathy, a subset of which were treated with doxycycline at different time points to suppress the tau transgene. Using this paradigm, we investigated the sensitivity of multiparametric MRI to both the accumulation and suppression of pathologic tau. Tau-related atrophy was discernible from 5.5 months within the cortex and hippocampus. We observed markedly less atrophy in the treated rTg4510 mice, which was enhanced after doxycycline intervention from 3.5 months. We also observed differences in amide proton transfer, cerebral blood flow, and diffusion tensor imaging parameters in the rTg4510 mice, which were significantly less altered after doxycycline treatment. We propose that these non-invasive MRI techniques offer insight into pathologic mechanisms underpinning Alzheimer's disease that may be important when evaluating emerging therapeutics targeting one of more of these processes. PMID:26923415

  1. Microfluidic laminate-based phantom for diffusion tensor-magnetic resonance imaging (DT-MRI)

    PubMed Central

    Samuel, R; Sant, H J; Jiao, F; Johnson, C R; Gale, B K

    2011-01-01

    This paper reports fabrication of a magnetic resonance imaging (MRI) phantom created by stacking of multiple thin polydimethylsiloxane (PDMS) layers. PDMS is spin coated on SU-8 molds to obtain the desired layer thickness and imprints of the microchannel patterns that define the phantom geometry. This paper also identifies the unique challenges related to the fabrication and assembly of multiple thin layers and reports for the first time assembly of a large number of thin laminates of this nature. Use of photolithography techniques allows us to create a wide range of phantom geometries. The target dimensions of the phantoms reported here are (i) a stack of 30 thin PDMS layers of 10 µm thickness (ii) curved 5 µm × 5 µm microchannels with 8.7 µm spacing, and (iii) straight 5 µm × 5 µm microchannels with 3.6 µm spacing. SEM scans of the assembled phantoms show open microchannels and a monolithic cross-section with no visible interface between PDMS layers. Based on the results of diffusion tensor magnetic resonance imaging (DT-MRI) scan, the anisotropic diffusion of water molecules due to the physical restriction of the microchannels was detected, which means that the phantom can be used to calibrate and optimize MRI instrumentation. PMID:22865956

  2. Mean Apparent Propagator (MAP) MRI: a novel diffusion imaging method for mapping tissue microstructure

    PubMed Central

    Özarslan, Evren; Koay, Cheng Guan; Shepherd, Timothy M.; Komlosh, Michal E.; İrfanoğlu, M. Okan; Pierpaoli, Carlo; Basser, Peter J.

    2014-01-01

    Diffusion-weighted magnetic resonance (MR) signals reflect information about underlying tissue microstructure and cytoarchitecture. We propose a quantitative, efficient, and robust mathematical and physical framework for representing diffusion-weighted MR imaging (MRI) data obtained in “q-space,” and the corresponding “mean apparent propagator (MAP)” describing molecular displacements in “r-space.” We also define and map novel quantitative descriptors of diffusion that can be computed robustly using this MAP-MRI framework. We describe efficient analytical representation of the three-dimensional q-space MR signal in a series expansion of basis functions that accurately describes diffusion in many complex geometries. The lowest order term in this expansion contains a diffusion tensor that characterizes the Gaussian displacement distribution, equivalent to diffusion tensor MRI (DTI). Inclusion of higher order terms enables the reconstruction of the true average propagator whose projection onto the unit “displacement” sphere provides an orientational distribution function (ODF) that contains only the orientational dependence of the diffusion process. The representation characterizes novel features of diffusion anisotropy and the non-Gaussian character of the three-dimensional diffusion process. Other important measures this representation provides include the return-to-the-origin probability (RTOP), and its variants for diffusion in one- and two-dimensions—the return-to-the-plane probability (RTPP), and the return-to-the-axis probability (RTAP), respectively. These zero net displacement probabilities measure the mean compartment (pore) volume and cross-sectional area in distributions of isolated pores irrespective of the pore shape. MAP-MRI represents a new comprehensive framework to model the three-dimensional q-space signal and transform it into diffusion propagators. Experiments on an excised marmoset brain specimen demonstrate that MAP-MRI

  3. Assessment of MRI Parameters as Imaging Biomarkers for Radiation Necrosis in the Rat Brain

    SciTech Connect

    Wang Silun; Tryggestad, Erik; Zhou Tingting; Armour, Michael; Wen Zhibo; Fu Dexue; Ford, Eric; Zijl, Peter C.M. van; Zhou Jinyuan

    2012-07-01

    Purpose: Radiation necrosis is a major complication of radiation therapy. We explore the features of radiation-induced brain necrosis in the rat, using multiple MRI approaches, including T{sub 1}, T{sub 2}, apparent diffusion constant (ADC), cerebral blood flow (CBF), magnetization transfer ratio (MTR), and amide proton transfer (APT) of endogenous mobile proteins and peptides. Methods and Materials: Adult rats (Fischer 344; n = 15) were irradiated with a single, well-collimated X-ray beam (40 Gy; 10 Multiplication-Sign 10 mm{sup 2}) in the left brain hemisphere. MRI was acquired on a 4.7-T animal scanner at {approx}25 weeks' postradiation. The MRI signals of necrotic cores and perinecrotic regions were assessed with a one-way analysis of variance. Histological evaluation was accomplished with hematoxylin and eosin staining. Results: ADC and CBF MRI could separate perinecrotic and contralateral normal brain tissue (p < 0.01 and < 0.05, respectively), whereas T{sub 1}, T{sub 2}, MTR, and APT could not. MRI signal intensities were significantly lower in the necrotic core than in normal brain for CBF (p < 0.001) and APT (p < 0.01) and insignificantly higher or lower for T{sub 1}, T{sub 2}, MTR, and ADC. Histological results demonstrated coagulative necrosis within the necrotic core and reactive astrogliosis and vascular damage within the perinecrotic region. Conclusion: ADC and CBF are promising imaging biomarkers for identifying perinecrotic regions, whereas CBF and APT are promising for identifying necrotic cores.

  4. Imaging of acute myocardial infarction in pigs with Indium-111 monoclonal antimyosin scintigraphy and MRI

    SciTech Connect

    ten Kate, C.I.; van Kroonenburgh, M.J.; Schipperheyn, J.J.; Doornbos, J.; Hoedemaeker, P.J.; Maes, A.; v.d. Nat, K.H.; Camps, J.A.; Huysmans, H.A.; Pauwels, E.K. )

    1990-07-01

    Indium-111 antimyosin F(ab')2 was used in a series of scintigraphic studies on experimentally induced myocardial infarctions in pigs. Antimyosin distribution recorded by planar images of in vivo pigs and by single photon emission computed tomography (SPECT) of excised hearts delineated areas of myocardial necrosis if infarct volume exceeded 3.3 cm3. Scintigraphic images were compared with magnetic resonance images (MRI) obtained from excised hearts and with photographs of slices of the hearts. Infarct size and localization determined with antimyosin were compared. The MR images, with or without gadolinium-DTPA (Gd-DTPA), of the in vivo pigs were all false-negative; some myocardial wall thinning and high bloodpool signals were visible. Results show that both the antimyosin and the MR technique are specific methods for the visualization of induced myocardial necrosis in this animal model. However, the use of antimyosin is limited to a period ranging from 24 to 72 hours after infarction.

  5. Voltage-based Device Tracking in a 1.5 Tesla MRI during Imaging: Initial validation in swine models

    PubMed Central

    Schmidt, Ehud J; Tse, Zion TH; Reichlin, Tobias R; Michaud, Gregory F; Watkins, Ronald D; Butts-Pauly, Kim; Kwong, Raymond Y; Stevenson, William; Schweitzer, Jeffrey; Byrd, Israel; Dumoulin, Charles L

    2013-01-01

    Purpose Voltage-based device-tracking (VDT) systems are commonly used for tracking invasive devices in electrophysiological (EP) cardiac-arrhythmia therapy. During EP procedures, electro-anatomic-mapping (EAM) workstations provide guidance by integrating VDT location and intra-cardiac-ECG information with X-ray, CT, Ultrasound, and MR images. MR assists navigation, mapping and radio-frequency-ablation. Multi-modality interventions require multiple patient transfers between an MRI and the X-ray/ultrasound EP suite, increasing the likelihood of patient-motion and image mis-registration. An MRI-compatible VDT system may increase efficiency, since there is currently no single method to track devices both inside and outside the MRI scanner. Methods An MRI-compatible VDT system was constructed by modifying a commercial system. Hardware was added to reduce MRI gradient-ramp and radio-frequency-unblanking-pulse interference. VDT patches and cables were modified to reduce heating. Five swine cardiac VDT EAM-mapping interventions were performed, navigating inside and thereafter outside the MRI. Results Three-catheter VDT interventions were performed at >12 frames-per-second both inside and outside the MRI scanner with <3mm error. Catheters were followed on VDT- and MRI-derived maps. Simultaneous VDT and imaging was possible in repetition-time (TR) >32 msec sequences with <0.5mm errors, and <5% MRI SNR loss. At shorter TRs, only intra-cardiac-ECG was reliable. RF Heating was <1.5C°. Conclusion An MRI-compatible VDT system is feasible. PMID:23580479

  6. Multimodal image registration of ex vivo 4 Tesla MRI with whole mount histology for prostate cancer detection

    NASA Astrophysics Data System (ADS)

    Chappelow, Jonathan; Madabhushi, Anant; Rosen, Mark; Tomaszeweski, John; Feldman, Michael

    2007-03-01

    In this paper we present novel methods for registration and subsequent evaluation of whole mount prostate histological sections to corresponding 4 Tesla ex vivo magnetic resonance imaging (MRI) slices to complement our existing computer-aided diagnosis (CAD) system for detection of prostatic adenocarcinoma from high resolution MRI. The CAD system is trained using voxels labeled as cancer on MRI by experts who visually aligned histology with MRI. To address voxel labeling errors on account of manual alignment and delineation, we have developed a registration method called combined feature ensemble mutual information (COFEMI) to automatically map spatial extent of prostate cancer from histology onto corresponding MRI for prostatectomy specimens. Our method improves over intensity-based similarity metrics (mutual information) by incorporating unique information from feature spaces that are relatively robust to intensity artifacts and which accentuate the structural details in the target and template images to be registered. Our registration algorithm accounts for linear gland deformations in the histological sections resulting from gland fixing and serial sectioning. Following automatic registration of MRI and histology, cancer extent from histological sections are mapped to the corresponding registered MRI slices. The manually delineated cancer areas on MRI obtained via manual alignment of histological sections and MRI are compared with corresponding cancer extent obtained via COFEMI by a novel registration evaluation technique based on use of non-linear dimensionality reduction (locally linear embedding (LLE)). The cancer map on MRI determined by COFEMI was found to be significantly more accurate compared to the manually determined cancer mask. The performance of COFEMI was also found to be superior compared to image intensity-based mutual information registration.

  7. Effect of contrast enhancement prior to iteration procedure on image correction for soft x-ray projection microscopy

    NASA Astrophysics Data System (ADS)

    Jamsranjav, Erdenetogtokh; Shiina, Tatsuo; Kuge, Kenichi; Kinjo, Yasuhito; Nakamura, Yuichi; Shinohara, Kunio; Ito, Atsushi

    2016-01-01

    Soft X-ray microscopy is well recognized as a powerful tool of high-resolution imaging for hydrated biological specimens. Projection type of it has characteristics of easy zooming function, simple optical layout and so on. However the image is blurred by the diffraction of X-rays, leading the spatial resolution to be worse. In this study, the blurred images have been corrected by an iteration procedure, i.e., Fresnel and inverse Fresnel transformations repeated. This method was confirmed by earlier studies to be effective. Nevertheless it was not enough to some images showing too low contrast, especially at high magnification. In the present study, we tried a contrast enhancement method to make the diffraction fringes clearer prior to the iteration procedure. The method was effective to improve the images which were not successful by iteration procedure only.

  8. Advances in functional and structural imaging of the human lung using proton MRI.

    PubMed

    Miller, G Wilson; Mugler, John P; Sá, Rui C; Altes, Talissa A; Prisk, G Kim; Hopkins, Susan R

    2014-12-01

    The field of proton lung MRI is advancing on a variety of fronts. In the realm of functional imaging, it is now possible to use arterial spin labeling (ASL) and oxygen-enhanced imaging techniques to quantify regional perfusion and ventilation, respectively, in standard units of measurement. By combining these techniques into a single scan, it is also possible to quantify the local ventilation-perfusion ratio, which is the most important determinant of gas-exchange efficiency in the lung. To demonstrate potential for accurate and meaningful measurements of lung function, this technique was used to study gravitational gradients of ventilation, perfusion, and ventilation-perfusion ratio in healthy subjects, yielding quantitative results consistent with expected regional variations. Such techniques can also be applied in the time domain, providing new tools for studying temporal dynamics of lung function. Temporal ASL measurements showed increased spatial-temporal heterogeneity of pulmonary blood flow in healthy subjects exposed to hypoxia, suggesting sensitivity to active control mechanisms such as hypoxic pulmonary vasoconstriction, and illustrating that to fully examine the factors that govern lung function it is necessary to consider temporal as well as spatial variability. Further development to increase spatial coverage and improve robustness would enhance the clinical applicability of these new functional imaging tools. In the realm of structural imaging, pulse sequence techniques such as ultrashort echo-time radial k-space acquisition, ultrafast steady-state free precession, and imaging-based diaphragm triggering can be combined to overcome the significant challenges associated with proton MRI in the lung, enabling high-quality three-dimensional imaging of the whole lung in a clinically reasonable scan time. Images of healthy and cystic fibrosis subjects using these techniques demonstrate substantial promise for non-contrast pulmonary angiography and detailed

  9. MRI 3D CISS– A Novel Imaging Modality in Diagnosing Trigeminal Neuralgia – A Review

    PubMed Central

    Besta, Radhika; Shankar, Y. Uday; Kumar, Ashwini; Prakash, S. Bhanu

    2016-01-01

    Trigeminal Neuralgia (TN) is considered as one of the most painful neurologic disorders affecting oro-facial region. TN is often diagnosed clinically based on the patients complete history of pain (severity, duration, episodes etc), relief of pain on test dose of Carbamazepine, regional block of long acting anaesthetic. However, Magnetic Resonance Imaging (MRI) plays an important and confirmatory role in showing Neuro Vascular Conflict (NVC) which is the commonest causative factor for TN. This article reviews the effectiveness of three-dimensional constructive interference in steady-state (3D-CISS) MRI in diagnosing the exact location, degree of neurovascular conflict responsible for classical as well as atypical TN and possible pre-treatment evaluation and treatment outcome. PMID:27135019

  10. Glucosamine and N-acetyl glucosamine as new CEST MRI agents for molecular imaging of tumors.

    PubMed

    Rivlin, Michal; Navon, Gil

    2016-01-01

    The efficacy of glucosamine (GlcN) and N-acetyl glucosamine (GlcNAc) as agents for chemical exchange saturation transfer (CEST) magnetic resonance molecular imaging of tumors is demonstrated. Both agents reflect the metabolic activity and malignancy of the tumors. The method was tested in two types of tumors implanted orthotopically in mice: 4T1 (mouse mammary cancer cells) and MCF7 (human mammary cancer cells). 4T1 is a more aggressive type of tumor than MCF7 and exhibited a larger CEST effect. Two methods of administration of the agents, intravenous (IV) and oral (PO), gave similar results. The CEST MRI observation of lung metastasis was confirmed by histology. The potential of the clinical application of CEST MRI with these agents for cancer diagnosis is strengthened by their lack of toxicity as can be indicated from their wide use as food supplements. PMID:27600054

  11. Glucosamine and N-acetyl glucosamine as new CEST MRI agents for molecular imaging of tumors

    PubMed Central

    Rivlin, Michal; Navon, Gil

    2016-01-01

    The efficacy of glucosamine (GlcN) and N-acetyl glucosamine (GlcNAc) as agents for chemical exchange saturation transfer (CEST) magnetic resonance molecular imaging of tumors is demonstrated. Both agents reflect the metabolic activity and malignancy of the tumors. The method was tested in two types of tumors implanted orthotopically in mice: 4T1 (mouse mammary cancer cells) and MCF7 (human mammary cancer cells). 4T1 is a more aggressive type of tumor than MCF7 and exhibited a larger CEST effect. Two methods of administration of the agents, intravenous (IV) and oral (PO), gave similar results. The CEST MRI observation of lung metastasis was confirmed by histology. The potential of the clinical application of CEST MRI with these agents for cancer diagnosis is strengthened by their lack of toxicity as can be indicated from their wide use as food supplements. PMID:27600054

  12. Breast density quantification using magnetic resonance imaging (MRI) with bias field correction: A postmortem study

    SciTech Connect

    Ding, Huanjun; Johnson, Travis; Lin, Muqing; Le, Huy Q.; Ducote, Justin L.; Su, Min-Ying; Molloi, Sabee

    2013-12-15

    Purpose: Quantification of breast density based on three-dimensional breast MRI may provide useful information for the early detection of breast cancer. However, the field inhomogeneity can severely challenge the computerized image segmentation process. In this work, the effect of the bias field in breast density quantification has been investigated with a postmortem study. Methods: T1-weighted images of 20 pairs of postmortem breasts were acquired on a 1.5 T breast MRI scanner. Two computer-assisted algorithms were used to quantify the volumetric breast density. First, standard fuzzy c-means (FCM) clustering was used on raw images with the bias field present. Then, the coherent local intensity clustering (CLIC) method estimated and corrected the bias field during the iterative tissue segmentation process. Finally, FCM clustering was performed on the bias-field-corrected images produced by CLIC method. The left–right correlation for breasts in the same pair was studied for both segmentation algorithms to evaluate the precision of the tissue classification. Finally, the breast densities measured with the three methods were compared to the gold standard tissue compositions obtained from chemical analysis. The linear correlation coefficient, Pearson'sr, was used to evaluate the two image segmentation algorithms and the effect of bias field. Results: The CLIC method successfully corrected the intensity inhomogeneity induced by the bias field. In left–right comparisons, the CLIC method significantly improved the slope and the correlation coefficient of the linear fitting for the glandular volume estimation. The left–right breast density correlation was also increased from 0.93 to 0.98. When compared with the percent fibroglandular volume (%FGV) from chemical analysis, results after bias field correction from both the CLIC the FCM algorithms showed improved linear correlation. As a result, the Pearson'sr increased from 0.86 to 0.92 with the bias field correction

  13. Breast MRI in Community Practice: Equipment and Imaging Techniques at Facilities in the Breast Cancer Surveillance Consortium (BCSC)

    PubMed Central

    DeMartini, Wendy B.; Ichikawa, Laura; Yankaskas, Bonnie C.; Buist, Diana; Kerlikowske, Karla; Geller, Berta; Onega, Tracy; Rosenberg, Robert D.; Lehman, Constance D.

    2010-01-01

    Purpose MRI is increasingly used for detection of breast carcinoma. Little is known about breast MRI techniques among community practice facilities. This study evaluated equipment and acquisition techniques used by community facilities across the U.S., including compliance with minimum standards by the American College of Radiology Imaging Network (ACRIN) 6667 Trial and the European Society of Breast Imaging (EUSOBI). Methods Breast Cancer Surveillance Consortium (BCSC) facilities performing breast MRI were identified and queried by survey regarding breast MRI equipment and technical parameters. Variables included scanner field strength, coil type, acquisition coverage, slice thickness and timing of initial post-contrast sequence. Results were tallied and percentages of facilities meeting ACRIN and EUSOBI standards were calculated Results From 23 facilities performing breast MRI, results were obtained from 14 (61%) facilities with 16 MRI scanners reporting 18 imaging parameters. Compliance with equipment recommendations of ≥1.5T field strength was 94% and of a dedicated breast coil was 100%. Eight-three percent of acquisitions used bilateral post-contrast technique and 78% used slice thickness <= 3 mm. Timing of initial post-contrast sequences ranged from 58 seconds to eight minutes 30 seconds, with 63% meeting recommendations for completion within four minutes. Conclusions Nearly all surveyed facilities met ACRIN and EUSOBI standards for breast MRI equipment. The majority met standards for acquisition parameters, although techniques varied, in particular for timing of initial post-contrast imaging. Further guidelines by the ACR Breast MRI Accreditation Program will be of importance in facilitating standardized and high quality breast MRI. PMID:21040870

  14. Transferring Cognitive Tasks Between Brain Imaging Modalities: Implications for Task Design and Results Interpretation in fMRI Studies

    PubMed Central

    Warbrick, Tracy; Reske, Martina; Shah, N. Jon

    2014-01-01

    As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. Here transferring a paradigm (the visual oddball task) with a long history of behavioral and electroencephalography (EEG) experiments to a functional magnetic resonance imaging (fMRI) experiment is considered. The aims of this paper are to briefly describe fMRI and when its use is appropriate in cognitive neuroscience; illustrate how task design can influence the results of an fMRI experiment, particularly when that task is borrowed from another imaging modality; explain the practical aspects of performing an fMRI experiment. It is demonstrated that manipulating the task demands in the visual oddball task results in different patterns of blood oxygen level dependent (BOLD) activation. The nature of the fMRI BOLD measure means that many brain regions are found to be active in a particular task. Determining the functions of these areas of activation is very much dependent on task design and analysis. The complex nature of many fMRI tasks means that the details of the task and its requirements need careful consideration when interpreting data. The data show that this is particularly important in those tasks relying on a motor response as well as cognitive elements and that covert and overt responses should be considered where possible. Furthermore, the data show that transferring an EEG paradigm to an fMRI experiment needs careful consideration and it cannot be assumed that the same paradigm will work equally well across imaging modalities. It is therefore recommended that the design of an fMRI study is pilot tested behaviorally to establish the effects of interest and then pilot tested in the fMRI environment to ensure appropriate design, implementation and analysis for the effects of interest. PMID:25285453

  15. Photoacoustic imaging of breast tumor vascularization: a comparison with MRI and histopathology

    NASA Astrophysics Data System (ADS)

    Heijblom, Michelle; Piras, Daniele; van den Engh, Frank M.; Klaase, Joost M.; Brinkhuis, Mariël.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-06-01

    Breast cancer is the most common form of cancer and the leading cause of cancer death among females. Early diagnosis improves the survival chances for the disease and that is why there is an ongoing search for improved methods for visualizing breast cancer. One of the hallmarks of breast cancer is the increase in tumor vascularization that is associated with angiogenesis: a crucial factor for survival of malignancies. Photoacoustic imaging can visualize the malignancyassociated increased hemoglobin concentration with optical contrast and ultrasound resolution, without the use of ionizing radiation or contrast agents and is therefore theoretically an ideal method for breast imaging. Previous clinical studies using the Twente Photoacoustic Mammoscope (PAM), which works in forward mode using a single wavelength (1064 nm), showed that malignancies can indeed be identified in the photoacoustic imaging volume as high contrast areas. However, the specific appearance of the malignancies led to questions about the contrast mechanism in relation to tumor vascularization. In this study, the photoacoustic lesion appearance obtained with an updated version of PAM is compared with the lesion appearance on Magnetic Resonance Imaging (MRI), both in general (19 patients) and on an individual basis (7 patients). Further, in 3 patients an extended histopathology protocol is being performed in which malignancies are stained for vascularity using an endothelial antibody: CD31. The correspondence between PAM and MRI and between PAM and histopathology makes it likely that the high photoacoustic contrast at 1064 nm is indeed largely the consequence of the increased tumor vascularization.

  16. Redox-responsive branched-bottlebrush polymers for in vivo MRI and fluorescence imaging

    PubMed Central

    Sowers, Molly A.; McCombs, Jessica R.; Wang, Ying; Paletta, Joseph T.; Morton, Stephen W.; Dreaden, Erik C.; Boska, Michael D.; Ottaviani, M. Francesca; Hammond, Paula T.; Rajca, Andrzej; Johnson, Jeremiah A.

    2014-01-01

    Stimuli-responsive multimodality imaging agents have broad potential in medical diagnostics. Herein, we report the development of a new class of branched-bottlebrush polymer dual-modality organic radical contrast agents—ORCAFluors—for combined magnetic resonance and near-infrared fluorescence imaging in vivo. These nitroxide radical-based nanostructures have longitudinal and transverse relaxation times that are on par with commonly used heavy-metal-based magnetic resonance imaging (MRI) contrast agents. Furthermore, these materials display a unique compensatory redox response: fluorescence is partially quenched by surrounding nitroxides in the native state; exposure to ascorbate or ascorbate/glutathione leads to nitroxide reduction and a concomitant 2- to 3.5-fold increase in fluorescence emission. This behaviour enables correlation of MRI contrast, fluorescence intensity and spin concentration with tissues known to possess high concentrations of ascorbate in mice. Our in vitro and in vivo results, along with our modular synthetic approach, make ORCAFluors a promising new platform for multimodality molecular imaging. PMID:25403521

  17. The Cyborg Astrobiologist: matching of prior textures by image compression for geological mapping and novelty detection

    NASA Astrophysics Data System (ADS)

    McGuire, P. C.; Bonnici, A.; Bruner, K. R.; Gross, C.; Ormö, J.; Smosna, R. A.; Walter, S.; Wendt, L.

    2014-07-01

    We describe an image-comparison technique of Heidemann and Ritter (2008a, b), which uses image compression, and is capable of: (i) detecting novel textures in a series of images, as well as of: (ii) alerting the user to the similarity of a new image to a previously observed texture. This image-comparison technique has been implemented and tested using our Astrobiology Phone-cam system, which employs Bluetooth communication to send images to a local laptop server in the field for the image-compression analysis. We tested the system in a field site displaying a heterogeneous suite of sandstones, limestones, mudstones and coal beds. Some of the rocks are partly covered with lichen. The image-matching procedure of this system performed very well with data obtained through our field test, grouping all images of yellow lichens together and grouping all images of a coal bed together, and giving 91% accuracy for similarity detection. Such similarity detection could be employed to make maps of different geological units. The novelty-detection performance of our system was also rather good (64% accuracy). Such novelty detection may become valuable in searching for new geological units, which could be of astrobiological interest. The current system is not directly intended for mapping and novelty detection of a second field site based on image-compression analysis of an image database from a first field site, although our current system could be further developed towards this end. Furthermore, the image-comparison technique is an unsupervised technique that is not capable of directly classifying an image as containing a particular geological feature; labelling of such geological features is done post facto by human geologists associated with this study, for the purpose of analysing the system's performance. By providing more advanced capabilities for similarity detection and novelty detection, this image-compression technique could be useful in giving more scientific autonomy

  18. Feasibility of magnetic resonance imaging (MRI) in obtaining nucleus pulposus (NP) water content with changing postures.

    PubMed

    Nazari, Jalil; Pope, Malcolm H; Graveling, Richard A

    2015-05-01

    Opportunities to evaluate spinal loading in vivo are limited and a large majority of studies on the mechanical functions of the spine have been in vitro cadaveric studies and/or models based on many assumptions that are difficult to validate. The purpose of this study was to investigate the feasibility of magnetic resonance imaging (MRI) in obtaining nucleus pulposus (NP) water content measurements with changing postures. MRI studies were conducted on 25 healthy males with no history of low back pain (age 20-38). The L1 to S1 intradiscal levels were imaged in supine, sitting and standing postures using an upright 0.6 Tesla magnet, where a set of H2O: D2O7 phantoms were mounted on the back of the subjects. A calibration curve, provided from these phantoms, was applied to the absolute proton density image, yielding a pixel-by-pixel map of the water content of the NP. The NP at all levels showed a highly significant water loss (p<0.001) in sitting and standing postures compared with the supine posture. A trend towards higher levels of water was observed at all levels in the standing posture relative to sitting postures, however statistically significant differences were found only at L4-L5 and L5-S1 levels. This study demonstrates that variations in water content of the NP in different postures are in agreement with those determined from published invasive disc pressure measurements. The result of study demonstrates the feasibility of using MRI to determine the water content of the NP with changing postures and to use these data to evaluate spinal loading in these postures. This measurement method of water content by quantitative MR imaging could become a powerful tool for both clinical and ergonomic applications. The proposed methodology does not require invasive pressure measurement techniques.

  19. Sodium and T1rho MRI for molecular and diagnostic imaging of articular cartilage.

    PubMed

    Borthakur, Arijitt; Mellon, Eric; Niyogi, Sampreet; Witschey, Walter; Kneeland, J Bruce; Reddy, Ravinder

    2006-11-01

    In this article, both sodium magnetic resonance (MR) and T1rho relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T1rho, a brief description of (i) principles of measuring T1rho relaxation, (ii) pulse sequences for computing T1rho relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T1rho in biological tissues and (v) effects of exchange and dipolar interaction on T1rho dispersion are discussed. Correlation of T1rho relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokine-induced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T1rho data from osteoarthritic specimens, animal models

  20. Audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI

    NASA Astrophysics Data System (ADS)

    Lee, D.; Greer, P. B.; Arm, J.; Keall, P.; Kim, T.

    2014-03-01

    The purpose of this study was to test the hypothesis that audiovisual (AV) biofeedback can improve image quality and reduce scan time for respiratory-gated 3D thoracic MRI. For five healthy human subjects respiratory motion guidance in MR scans was provided using an AV biofeedback system, utilizing real-time respiratory motion signals. To investigate the improvement of respiratory-gated 3D MR images between free breathing (FB) and AV biofeedback (AV), each subject underwent two imaging sessions. Respiratory-related motion artifacts and imaging time were qualitatively evaluated in addition to the reproducibility of external (abdominal) motion. In the results, 3D MR images in AV biofeedback showed more anatomic information such as a clear distinction of diaphragm, lung lobes and sharper organ boundaries. The scan time was reduced from 401±215 s in FB to 334±94 s in AV (p-value 0.36). The root mean square variation of the displacement and period of the abdominal motion was reduced from 0.4±0.22 cm and 2.8±2.5 s in FB to 0.1±0.15 cm and 0.9±1.3 s in AV (p-value of displacement <0.01 and p-value of period 0.12). This study demonstrated that audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI. These results suggest that AV biofeedback has the potential to be a useful motion management tool in medical imaging and radiation therapy procedures.

  1. MRI Inner Ear Imaging and Tone Burst Electrocochleography in the Diagnosis of Ménière’s Disease

    PubMed Central

    Hornibrook, Jeremy; Flook, Edward; Greig, Sam; Babbage, Melissa; Goh, Tony; Coates, Mark; Care, Rachel; Bird, Philip

    2015-01-01

    Objective To compare the sensitivity of gadolinium MRI inner imaging with tone burst electrocochleography (EcochG) for diagnosing endolymphatic hydrops. Study Design A prospective study on patients who were to have an MRI scan to exclude retrocochlear pathology. Setting Tertiary care center. Patients One hundred and two patients: 57 patients with Possible, Probable, or Definite Ménière’s Disease, 25 with asymmetrical hearing loss, 18 with sudden sensorineural hearing loss, and 2 with unilateral tinnitus had additional MRI inner ear imaging and click and tone burst stimulus EcochG testing. Intervention Diagnostic. Main Outcome Measure To compare the sensitivity of the two techniques. Results In 30 patients with symptom-based Definite Ménière’s Disease, tone burst EcochG was positive in 25 (83%) and the click EcochG was positive in 9/30 (30%), and gadolinium MRI imaging diagnosed hydrops in 14 (47%). A positive result for either MRI imaging or tone burst EcochG was seen in 26 patients (87%). In 14 subjects with symptom-based Probable Ménière’s Disease, 10 (71%) had either a positive EcochG or MRI. In 13 with Possible Ménière’s Disease, four (31%) had a positive EcochG or MRI. Conclusion This study confirms the greatly enhanced diagnostic sensitivity of tone burst EcochG over click response in diagnosing endolymphatic hydrops in Ménière’s disease. Even though adequate MRI imaging was achieved in 90%, tone burst EcochG was a more sensitive test. PMID:25985318

  2. Simultaneous steering and imaging of magnetic particles using MRI toward delivery of therapeutics

    PubMed Central

    Felfoul, Ouajdi; Becker, Aaron T.; Fagogenis, Georgios; Dupont, Pierre E.

    2016-01-01

    Magnetic resonance navigation (MRN) offers the potential for real-time steering of drug particles and cells to targets throughout the body. In this technique, the magnetic gradients of an MRI scanner perform image-based steering of magnetically-labelled therapeutics through the vasculature and into tumours. A major challenge of current techniques for MRN is that they alternate between pulse sequences for particle imaging and propulsion. Since no propulsion occurs while imaging the particles, this results in a significant reduction in imaging frequency and propulsive force. We report a new approach in which an imaging sequence is designed to simultaneously image and propel particles. This sequence provides a tradeoff between maximum propulsive force and imaging frequency. In our reported example, the sequence can image at 27 Hz while still generating 95% of the force produced by a purely propulsive pulse sequence. We implemented our pulse sequence on a standard clinical scanner using millimetre-scale particles and demonstrated high-speed (74 mm/s) navigation of a multi-branched vascular network phantom. Our study suggests that the magnetic gradient magnitudes previously demonstrated to be sufficient for pure propulsion of micron-scale therapeutics in magnetic resonance targeting (MRT) could also be sufficient for real-time steering of these particles. PMID:27666666

  3. MRI Based Preterm White Matter Injury Classification: The Importance of Sequential Imaging in Determining Severity of Injury

    PubMed Central

    Martinez-Biarge, Miriam; Groenendaal, Floris; Kersbergen, Karina J.; Benders, Manon J. N. L.; Foti, Francesca; Cowan, Frances M.; de Vries, Linda S.

    2016-01-01

    Background The evolution of non-hemorrhagic white matter injury (WMI) based on sequential magnetic resonance imaging (MRI) has not been well studied. Our aim was to describe sequential MRI findings in preterm infants with non-hemorrhagic WMI and to develop an MRI classification system for preterm WMI based on these findings. Methods Eighty-two preterm infants (gestation ≤35 weeks) were retrospectively included. WMI was diagnosed and classified based on sequential cranial ultrasound (cUS) and confirmed on MRI. Results 138 MRIs were obtained at three time-points: early (<2 weeks; n = 32), mid (2–6 weeks; n = 30) and term equivalent age (TEA; n = 76). 63 infants (77%) had 2 MRIs during the neonatal period. WMI was non-cystic in 35 and cystic in 47 infants. In infants with cystic-WMI early MRI showed extensive restricted diffusion abnormalities, cysts were already present in 3 infants; mid MRI showed focal or extensive cysts, without acute diffusion changes. A significant reduction in the size and/or extent of the cysts was observed in 32% of the infants between early/mid and TEA MRI. In 4/9 infants previously seen focal cysts were no longer identified at TEA. All infants with cystic WMI showed ≥2 additional findings at TEA: significant reduction in WM volume, mild-moderate irregular ventriculomegaly, several areas of increased signal intensity on T1-weighted-images, abnormal myelination of the PLIC, small thalami. Conclusion In infants with extensive WM cysts at 2–6 weeks, cysts may be reduced in number or may even no longer be seen at TEA. A single MRI at TEA, without taking sequential cUS data and pre-TEA MRI findings into account, may underestimate the extent of WMI; based on these results we propose a new MRI classification for preterm non-hemorrhagic WMI. PMID:27257863

  4. Prior Image Guided Undersampled Dual Energy Reconstruction with Piecewise Polynomial Function Constraint

    PubMed Central

    Zhang, Li; Li, Liang; Shen, Le; Xing, Yuxiang

    2013-01-01

    Dual energy CT has the ability to give more information about the test object by reconstructing the attenuation factors under different energies. These images under different energies share identical structures but different attenuation factors. By referring to the fully sampled low-energy image, we show that it is possible to greatly reduce the sampling rate of the high-energy image in order to lower dose. To compensate the attenuation factor difference between the two modalities, we use piecewise polynomial fitting to fit the low-energy image to the high-energy image. During the reconstruction, the result is constrained by its distance to the fitted image, and the structural information thus can be preserved. An ASD-POCS-based optimization schedule is proposed to solve the problem, and numerical simulations are taken to verify the algorithm. PMID:24282443

  5. Cilengitide inhibits progression of experimental breast cancer bone metastases as imaged noninvasively using VCT, MRI and DCE-MRI in a longitudinal in vivo study.

    PubMed

    Bäuerle, Tobias; Komljenovic, Dorde; Merz, Maximilian; Berger, Martin R; Goodman, Simon L; Semmler, Wolfhard

    2011-05-15

    The aim of this study was to investigate the effect of inhibiting αvβ(3)/α(v) β(5) integrins by cilengitide in experimentally induced breast cancer bone metastases using noninvasive imaging techniques. For this purpose, nude rats bearing established breast cancer bone metastases were treated with cilengitide, a small molecule inhibitor of αvβ(3) and αvβ(5) integrins (75 mg/kg, five days per week; n = 12 rats) and compared to vehicle-treated control rats (n = 12). In a longitudinal study, conventional magnetic resonance imaging (MRI) and flat panel volumetric computed tomography were used to assess the volume of the soft tissue tumor and osteolysis, respectively, and dynamic contrast-enhanced (DCE-) MRI was performed to determine functional parameters of the tumor vasculature reflecting blood volume and blood vessel permeability. In rats treated with cilengitide, VCT and MRI showed that osteolytic lesions and the respective bone metastatic soft tissue tumors progressed more slowly than in vehicle-treated controls. DCE-MRI indicated a decrease in blood volume and an increase in vessel permeability and immunohistology revealed increased numbers of immature vessels in cilengitide-treated rats compared to vehicle controls. In conclusion, treatment of experimental breast cancer bone metastases with cilengitide resulted in pronounced antiresorptive and antitumor effects, suggesting that αvβ(3)/αvβ(5) inhibition may be a promising therapeutic approach for bone metastases. PMID:20648558

  6. A prior-knowledge-based threshold segmentation method of forward-looking sonar images for underwater linear object detection

    NASA Astrophysics Data System (ADS)

    Liu, Lixin; Bian, Hongyu; Yagi, Shin-ichi; Yang, Xiaodong

    2016-07-01

    Raw sonar images may not be used for underwater detection or recognition directly because disturbances such as the grating-lobe and multi-path disturbance affect the gray-level distribution of sonar images and cause phantom echoes. To search for a more robust segmentation method with a reasonable computational cost, a prior-knowledge-based threshold segmentation method of underwater linear object detection is discussed. The possibility of guiding the segmentation threshold evolution of forward-looking sonar images using prior knowledge is verified by experiment. During the threshold evolution, the collinear relation of two lines that correspond to double peaks in the voting space of the edged image is used as the criterion of termination. The interaction is reflected in the sense that the Hough transform contributes to the basis of the collinear relation of lines, while the binary image generated from the current threshold provides the resource of the Hough transform. The experimental results show that the proposed method could maintain a good tradeoff between the segmentation quality and the computational time in comparison with conventional segmentation methods. The proposed method redounds to a further process for unsupervised underwater visual understanding.

  7. Complimentary aspects of diffusion imaging and fMRI: II. Elucidating contributions to the fMRI signal with diffusion sensitization.

    PubMed

    Mulkern, Robert V; Haker, Steven J; Maier, Stephan E

    2007-07-01

    Tissue water molecules reside in different biophysical compartments. For example, water molecules in the vasculature reside for variable periods of time within arteries, arterioles, capillaries, venuoles and veins, and may be within blood cells or blood plasma. Water molecules outside of the vasculature, in the extravascular space, reside, for a time, either within cells or within the interstitial space between cells. Within these different compartments, different types of microscopic motion that water molecules may experience have been identified and discussed. These range from Brownian diffusion to more coherent flow over the time scales relevant to functional magnetic resonance imaging (fMRI) experiments, on the order of several 10s of milliseconds. How these different types of motion are reflected in magnetic resonance imaging (MRI) methods developed for "diffusion" imaging studies has been an ongoing and active area of research. Here we briefly review the ideas that have developed regarding these motions within the context of modern "diffusion" imaging techniques and, in particular, how they have been accessed in attempts to further our understanding of the various contributions to the fMRI signal changes sought in studies of human brain activation. PMID:17442520

  8. Evaluating pH in the Extracellular Tumor Microenvironment Using CEST MRI and Other Imaging Methods

    PubMed Central

    Chen, Liu Qi; Pagel, Mark D.

    2016-01-01

    Tumor acidosis is a consequence of altered metabolism, which can lead to chemoresistance and can be a target of alkalinizing therapies. Noninvasive measurements of the extracellular pH (pHe) of the tumor microenvironment can improve diagnoses and treatment decisions. A variety of noninvasive imaging methods have been developed for measuring tumor pHe. This review provides a detailed description of the advantages and limitations of each method, providing many examples from previous research reports. A substantial emphasis is placed on methods that use MR spectroscopy and MR imaging, including recently developed methods that use chemical exchange saturation transfer MRI that combines some advantages of MR spectroscopy and imaging. Together, this review provides a comprehensive overview of methods for measuring tumor pHe, which may facilitate additional creative approaches in this research field. PMID:27761517

  9. Fat Imaging via Magnetic Resonance Imaging (MRI) in Young Children (Ages 1-4 Years) without Sedation

    PubMed Central

    Shearrer, Grace E.; House, Benjamin T.; Gallas, Michelle C.; Luci, Jeffrey J.; Davis, Jaimie N.

    2016-01-01

    Introduction This pilot study developed techniques to perform Magnetic Resonance Imaging (MRI) of specific fat deposition in 18 children (age 18 months to 4 years). Methods The children engaged in a series of practice tests to become acclimated to the scanner noises, reduce claustrophobia, and rehearse holding still for a set time. The practice tests assessed if the child could remain still for two minutes while watching a video, first while lying on a blanket, second, on the blanket with headphones, and third, in the mock scanner. The children who passed the three practice tests were then scanned with a 3T Siemens Skyra magnet. Abdominal fat distribution (region of interest (ROI) from the top of the ileac crest to the bottom of the ribcage) volume was measured using 2-point DIXON technique. This region was chosen to give an indication of the body composition around the liver. Results Twelve out of eighteen participants successfully completed the actual MRI scan. Chi-squared test showed no significant difference between male and female pass-fail rates. The median age of completed scans was 36 months, whereas the median age for children unable to complete a scan was 28 months. The average total trunk fat was 240.9±85.2mL and the average total VAT was 37.7±25.9mLand liver fat was not quantifiable due to physiological motion. Several strategies (modeling, videos, and incentives) were identified to improve pediatric imaging in different age ranges. Conclusion Using an age-specific and tailored protocol, we were able to successfully use MRI for fat imaging in a majority of young children. Development of such protocols enables researchers to better understand the etiology of fat deposition in young children, which can be used to aid in the prevention and treatment of adiposity. PMID:26901881

  10. Prediction of background parenchymal enhancement on breast MRI using mammography, ultrasonography, and diffusion-weighted imaging

    PubMed Central

    Kawamura, Akiko; Satake, Hiroko; Ishigaki, Satoko; Ikeda, Mitsuru; Kimura, Reiko; Shimamoto, Kazuhiro; Naganawa, Shinji

    2015-01-01

    ABSTRACT This retrospective study assessed the effects of menopausal status and menstrual cycle on background parenchymal enhancement (BPE) of breast magnetic resonance imaging (MRI), and investigated whether the degree of BPE can be predicted by findings of mammography, ultrasonography (US), and diffusion-weighted MR imaging (DWI). There were 160 study patients (80 premenopausal, 80 postmenopausal). Degree of BPE was classified into minimal, mild, moderate, or marked. Mammographic density was classified into fatty, scattered, heterogeneously dense, and extremely dense. BP echotexture on US and BP intensity on DWI were visually classified as homogeneous or heterogeneous. Apparent diffusion coefficient (ADC) values of normal breast tissue were measured. Associations of the degree of BPE with menopausal status, menstrual cycle, or imaging features were evaluated by univariate and multivariate analyses. No significant correlation was found between mammographic density and BPE (p=0.085), whereas menopausal status (p=0.000), BP echotexture (p=0.000), and BP intensity on DWI (p= 0.000), and ADC values (p=0.000) showed significant correlations with BPE. Multivariate analysis showed that postmenopausal status was an independent predictor of minimal BPE (p=0.002, OR=3.743). In premenopausal women, there was no significant correlation between menstrual cycle and BPE, whereas BP echotexture was an independent predictor of whether BPE was less than mild or greater than moderate (p=0.001, OR=26.575). BPE on breast MRI is associated with menopausal status and the findings of US and DWI. Because premenopausal women with heterogeneous BP echotexture may be predicted to show moderate or marked BPE, scheduling of breast MRI should preferentially be adjusted to the menstrual cycle. PMID:26412889

  11. Effect of Imaging Parameter Thresholds on MRI Prediction of Neoadjuvant Chemotherapy Response in Breast Cancer Subtypes

    PubMed Central

    Jones, Ella F.; Newitt, David C.; Kornak, John; Wilmes, Lisa J.; Esserman, Laura J.; Hylton, Nola M.

    2016-01-01

    The purpose of this study is to evaluate the predictive performance of magnetic resonance imaging (MRI) markers in breast cancer patients by subtype. Sixty-four patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy were enrolled in this study. Each patient received a dynamic contrast-enhanced (DCE-MRI) at baseline, after 1 cycle of chemotherapy and before surgery. Functional tumor volume (FTV), the imaging marker measured by DCE-MRI, was computed at various thresholds of percent enhancement (PEt) and signal-enhancement ratio (SERt). Final FTV before surgery and percent changes of FTVs at the early and final treatment time points were used to predict patients’ recurrence-free survival. The full cohort and each subtype defined by the status of hormone receptor and human epidermal growth factor receptor 2 (HR+/HER2-, HER2+, triple negative) were analyzed. Predictions were evaluated using the Cox proportional hazard model when PEt changed from 30% to 200% in steps of 10% and SERt changed from 0 to 2 in steps of 0.2. Predictions with high hazard ratios and low p-values were considered as strong. Different profiles of FTV as predictors for recurrence-free survival were observed in each breast cancer subtype and strong associations with survival were observed at different PEt/SERt combinations that resulted in different FTVs. Findings from this retrospective study suggest that the predictive performance of imaging markers based on FTV may be improved with enhancement thresholds being optimized separately for clinically-relevant subtypes defined by HR and HER2 receptor expression. PMID:26886725

  12. 1.5 Tesla MRI-Conditional 12-lead ECG for MR Imaging and Intra-MR Intervention

    PubMed Central

    Tse, Zion Tsz Ho; Dumoulin, Charles L.; Clifford, Gari D.; Schweitzer, Jeff; Qin, Lei; Oster, Julien; Jerosch-Herold, Michael; Kwong, Raymond Y.; Michaud, Gregory; Stevenson, William G.; Schmidt, Ehud J.

    2013-01-01

    Propose High-fidelity 12-lead Electrocardiogram (ECG) is important for physiological monitoring of patients during MR-guided intervention and cardiac MR imaging. Issues in obtaining non-corrupted ECGs inside MRI include a superimposed Magneto-Hydro-Dynamic (MHD) voltage, gradient-switching induced-voltages, and radiofrequency (RF) heating. These problems increase with magnetic field. We intended to develop and clinically validate a 1.5T MRI-conditional 12-lead ECG system. Methods The system was constructed, including transmission-lines to reduce radio-frequency induction, and switching-circuits to remove induced voltages. Adaptive filters, trained by 12-lead measurements outside MRI and in two orientations inside MRI, were used to remove MHD. The system was tested on ten (one exercising) volunteers and four arrhythmia patients. Results Switching circuits removed most imaging-induced voltages (residual noise <3% of the R-wave). MHD removal provided intra-MRI ECGs that varied by <3.8% from those outside the MRI, preserving the true ST segment. In premature-ventricular-contraction (PVC) patients, clean ECGs separated PVC and sinus-rhythm beats. Measured heating was <1.5 C0. The system reliably acquired multiphase (SSFP) wall-motion-cine and phase-contrast-cine scans, including in subjects where 4-lead gating failed. The system required a minimum TR of 4ms to allow robust ECG processing. Conclusion High-fidelity intra-MRI 12-lead ECG is possible. PMID:23580148

  13. Tissue Tracking: Applications for Brain MRI Classification

    PubMed Central

    Melonakos, John; Gao, Yi; Tannenbaum, Allen

    2013-01-01

    Bayesian classification methods have been extensively used in a variety of image processing applications, including medical image analysis. The basic procedure is to combine data-driven knowledge in the likelihood terms with clinical knowledge in the prior terms to classify an image into a pre-determined number of classes. In many applications, it is difficult to construct meaningful priors and, hence, homogeneous priors are assumed. In this paper, we show how expectation-maximization weights and neighboring posterior probabilities may be combined to make intuitive use of the Bayesian priors. Drawing upon insights from computer vision tracking algorithms, we cast the problem in a tissue tracking framework. We show results of our algorithm on the classification of gray and white matter along with surrounding cerebral spinal fluid in brain MRI scans. We show results of our algorithm on 20 brain MRI datasets along with validation against expert manual segmentations. PMID:24392193

  14. Tissue tracking: applications for brain MRI classification

    NASA Astrophysics Data System (ADS)

    Melonakos, John; Gao, Yi; Tannenbaum, Allen

    2007-03-01

    Bayesian classification methods have been extensively used in a variety of image processing applications, including medical image analysis. The basic procedure is to combine data-driven knowledge in the likelihood terms with clinical knowledge in the prior terms to classify an image into a pre-determined number of classes. In many applications, it is difficult to construct meaningful priors and, hence, homogeneous priors are assumed. In this paper, we show how expectation-maximization weights and neighboring posterior probabilities may be combined to make intuitive use of the Bayesian priors. Drawing upon insights from computer vision tracking algorithms, we cast the problem in a tissue tracking framework. We show results of our algorithm on the classification of gray and white matter along with surrounding cerebral spinal fluid in brain MRI scans. We show results of our algorithm on 20 brain MRI datasets along with validation against expert manual segmentations.

  15. A robust independent component analysis (ICA) model for functional magnetic resonance imaging (fMRI) data

    NASA Astrophysics Data System (ADS)

    Ao, Jingqi; Mitra, Sunanda; Liu, Zheng; Nutter, Brian

    2011-03-01

    The coupling of carefully designed experiments with proper analysis of functional magnetic resonance imaging (fMRI) data provides us with a powerful as well as noninvasive tool to help us understand cognitive processes associated with specific brain regions and hence could be used to detect abnormalities induced by a diseased state. The hypothesisdriven General Linear Model (GLM) and the data-driven Independent Component Analysis (ICA) model are the two most commonly used models for fMRI data analysis. A hybrid ICA-GLM model combines the two models to take advantages of benefits from both models to achieve more accurate mapping of the stimulus-induced activated brain regions. We propose a modified hybrid ICA-GLM model with probabilistic ICA that includes a noise model. In this modified hybrid model, a probabilistic principle component analysis (PPCA)-based component number estimation is used in the ICA stage to extract the intrinsic number of original time courses. In addition, frequency matching is introduced into the time course selection stage, along with temporal correlation, F-test based model fitting estimation, and time course combination, to produce a more accurate design matrix for GLM. A standard fMRI dataset is used to compare the results of applying GLM and the proposed hybrid ICA-GLM in generating activation maps.

  16. A Novel liposomal nanoparticle for the imaging of amyloid plaque by MRI

    PubMed Central

    Tanifum, Eric A.; Ghaghada, Ketan; Vollert, Craig; Head, Elizabeth; Eriksen, Jason L.; Annapragada, Ananth

    2016-01-01

    Amyloid binding molecules with greater hydrophilicity than existing ligands were synthesized. The lead candidate ET6-21 bound amyloid fibrils, and amyloid deposits in dog brain and human brain tissue ex vivo. The ligand was used to prepare novel amyloid-targeted liposomal nanoparticles. The preparation was tested in the Tg2576 and TetO/APP mouse models of amyloid deposition. Gd chelates and Indocyanine green were included in the particles for visualization by MRI and near-infrared microscopy. Upon intravenous injection, the particles successfully traversed the blood-brain barrier in these mice, and bound to the plaques. Magnetic resonance imaging (T1-MRI) conducted 4 days after injection demonstrated elevated signal in the brains of mice with amyloid plaques present. No signal was observed in amyloid-negative mice, or in amyloid-positive mice injected with an untargeted version of the same agent. The MRI results were confirmed by immunohistochemical and fluorescent microscopic examination of mouse brain sections, showing colocalization of the fluorescent tags and amyloid deposits. PMID:27031484

  17. A Quantitative MRI Method for Imaging Blood-Brain Barrier Leakage in Experimental Traumatic Brain Injury

    PubMed Central

    Watts, Lora Talley; Jiang, Zhao; Shen, Qiang; Li, Yunxia; Duong, Timothy Q.

    2014-01-01

    Blood-brain barrier (BBB) disruption is common following traumatic brain injury (TBI). Dynamic contrast enhanced (DCE) MRI can longitudinally measure the transport coefficient Ktrans which reflects BBB permeability. Ktrans measurements however are not widely used in TBI research because it is generally considered to be noisy and possesses low spatial resolution. We improved spatiotemporal resolution and signal sensitivity of Ktrans MRI in rats by using a high-sensitivity surface transceiver coil. To overcome the signal drop off profile of the surface coil, a pre-scan module was used to map the flip angle (B1 field) and magnetization (M0) distributions. A series of T1-weighted gradient echo images were acquired and fitted to the extended Kety model with reversible or irreversible leakage, and the best model was selected using F-statistics. We applied this method to study the rat brain one hour following controlled cortical impact (mild to moderate TBI), and observed clear depiction of the BBB damage around the impact regions, which matched that outlined by Evans Blue extravasation. Unlike the relatively uniform T2 contrast showing cerebral edema, Ktrans shows a pronounced heterogeneous spatial profile in and around the impact regions, displaying a nonlinear relationship with T2. This improved Ktrans MRI method is also compatible with the use of high-sensitivity surface coil and the high-contrast two-coil arterial spin-labeling method for cerebral blood flow measurement, enabling more comprehensive investigation of the pathophysiology in TBI. PMID:25478693

  18. Targeted Multifunctional Nanoparticles cure and image Brain Tumors: Selective MRI Contrast Enhancement and Photodynamic Therapy

    NASA Astrophysics Data System (ADS)

    Kopelman, Raoul

    2008-03-01

    Aimed at targeted therapy and imaging of brain tumors, our approach uses targeted, multi-functional nano-particles (NP). A typical nano-particle contains a biologically inert, non-toxic matrix, biodegradable and bio-eliminable over a long time period. It also contains active components, such as fluorescent chemical indicators, photo-sensitizers, MRI contrast enhancement agents and optical imaging dyes. In addition, its surface contains molecular targeting units, e.g. peptides or antibodies, as well as a cloaking agent, to prevent uptake by the immune system, i.e. enabling control of the plasma residence time. These dynamic nano-platforms (DNP) contain contrast enhancement agents for the imaging (MRI, optical, photo-acoustic) of targeted locations, i.e. tumors. Added to this are targeted therapy agents, such as photosensitizers for photodynamic therapy (PDT). A simple protocol, for rats implanted with human brain cancer, consists of tail injection with DNPs, followed by 5 min red light illumination of the tumor region. It resulted in excellent cure statistics for 9L glioblastoma.

  19. PROMO: Real-time prospective motion correction in MRI using image-based tracking.

    PubMed

    White, Nathan; Roddey, Cooper; Shankaranarayanan, Ajit; Han, Eric; Rettmann, Dan; Santos, Juan; Kuperman, Josh; Dale, Anders

    2010-01-01

    Artifacts caused by patient motion during scanning remain a serious problem in most MRI applications. The prospective motion correction technique attempts to address this problem at its source by keeping the measurement coordinate system fixed with respect to the patient throughout the entire scan process. In this study, a new image-based approach for prospective motion correction is described, which utilizes three orthogonal two-dimensional spiral navigator acquisitions, along with a flexible image-based tracking method based on the extended Kalman filter algorithm for online motion measurement. The spiral navigator/extended Kalman filter framework offers the advantages of image-domain tracking within patient-specific regions-of-interest and reduced sensitivity to off-resonance-induced corruption of rigid-body motion estimates. The performance of the method was tested using offline computer simulations and online in vivo head motion experiments. In vivo validation results covering a broad range of staged head motions indicate a steady-state error of less than 10% of the motion magnitude, even for large compound motions that included rotations over 15 deg. A preliminary in vivo application in three-dimensional inversion recovery spoiled gradient echo (IR-SPGR) and three-dimensional fast spin echo (FSE) sequences demonstrates the effectiveness of the spiral navigator/extended Kalman filter framework for correcting three-dimensional rigid-body head motion artifacts prospectively in high-resolution three-dimensional MRI scans.

  20. Registering fNIR data to brain surface image using MRI templates.

    PubMed

    Ayaz, Hasan; Izzetoglu, Meltem; Platek, Steven M; Bunce, Scott; Izzetoglu, Kurtulus; Pourrezaei, Kambiz; Onaral, Banu

    2006-01-01

    Functional near-infrared spectroscopy (fNIR) measures changes in the relative levels of oxygenated and deoxygenated hemoglobin and has increasingly been used to assess neural functioning in the brain. In addition to the ongoing technological developments, investigators have also been conducting studies on functional mapping and refinement of data analytic strategies in order to better understand the relationship between the fNIR signal and brain activity. However, since fNIR is a relatively new functional brain imaging modality as compared to positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), it still lacks brain-mapping tools designed to allow researchers and clinicians to easily interact with their data. The aim of this study is to develop a registration technique for the fNIR measurements using anatomical landmarks and structural magnetic resonance imaging (MRI) templates in order to visualize the brain activation when and where it happens. The proposed registration technique utilizes chain-code algorithm and depicts activations over respective locations based on sensor geometry. Furthermore, registered data locations have been used to create spatiotemporal visualization of fNIR measurements.

  1. Assessment of Geometrical Accuracy of Multimodal Images Used for Treatment Planning in Stereotactic Radiotherapy and Radiosurgery: CT, MRI and PET

    SciTech Connect

    Garcia-Garduno, O. A.; Larraga-Gutierrez, J. M.; Celis, M. A.; Suarez-Campos, J. J.; Rodriguez-Villafuerte, M.; Martinez-Davalos, A.

    2006-09-08

    An acrylic phantom was designed and constructed to assess the geometrical accuracy of CT, MRI and PET images for stereotactic radiotherapy (SRT) and radiosurgery (SRS) applications. The phantom was suited for each image modality with a specific tracer and compared with CT images to measure the radial deviation between the reference marks in the phantom. It was found that for MRI the maximum mean deviation is 1.9 {+-} 0.2 mm compared to 2.4 {+-} 0.3 mm reported for PET. These results will be used for margin outlining in SRS and SRT treatment planning.

  2. Cardiac Amyloidosis: Typical Imaging Findings and Diffuse Myocardial Damage Demonstrated by Delayed Contrast-Enhanced MRI

    SciTech Connect

    Sueyoshi, Eijun Sakamoto, Ichiro; Okimoto, Tomoaki; Hayashi, Kuniaki; Tanaka, Kyouei; Toda, Genji

    2006-08-15

    Amyloidosis is a rare systemic disease. However, involvement of the heart is a common finding and is the most frequent cause of death in amyloidosis. We report the sonographic, scintigraphic, and MRI features of a pathologically proven case of cardiac amyloidosis. Delayed contrast-enhanced MR images, using an inversion recovery prepped gradient-echo sequence, revealed diffuse enhancement in the wall of both left and right ventricles. This enhancement suggested expansion of the extracellular space of the myocardium caused by diffuse myocardial necrosis secondary to deposition of amyloid.

  3. High-Relaxivity MRI Contrast Agents: Where Coordination Chemistry Meets Medical Imaging

    SciTech Connect

    Werner, Eric J.; Datta, Ankona; Jocher, Christoph J.; Raymond, Kenneth N.

    2008-01-15

    The desire to improve and expand the scope of clinical magnetic resonance imaging (MRI) has prompted the search for contrast agents of higher efficiency. The development of better agents requires consideration of the fundamental coordination chemistry of the gadolinium(III) ion and the parameters that affect its efficacy as a proton relaxation agent. In optimizing each parameter, other practical issues such as solubility and in vivo toxicity must also be addressed, making the attainment of safe, high-relaxivity agents a challenging goal. Here we present recent advances in the field, with an emphasis on the hydroxypyridinone family of Gd{sup III} chelates.

  4. Genetic engineered molecular imaging probes for applications in cell therapy: emphasis on MRI approach

    PubMed Central

    Cho, In K; Wang, Silun; Mao, Hui; Chan, Anthony WS

    2016-01-01

    Recent advances in stem cell-based regenerative medicine, cell replacement therapy, and genome editing technologies (i.e. CRISPR-Cas 9) have sparked great interest in in vivo cell monitoring. Molecular imaging promises a unique approach to noninvasively monitor cellular and molecular phenomena, including cell survival, migration, proliferation, and even differentiation at the whole organismal level. Several imaging modalities and strategies have been explored for monitoring cell grafts in vivo. We begin this review with an introduction describing the progress in stem cell technology, with a perspective toward cell replacement therapy. The importance of molecular imaging in reporting and assessing the status of cell grafts and their relation to the local microenvironment is highlighted since the current knowledge gap is one of the major obstacles in clinical translation of stem cell therapy. Based on currently available imaging techniques, we provide a brief discussion on the pros and cons of each imaging modality used for monitoring cell grafts with particular emphasis on magnetic resonance imaging (MRI) and the reporter gene approach. Finally, we conclude with a comprehensive discussion of future directions of applying molecular imaging in regenerative medicine to emphasize further the importance of correlating cell graft conditions and clinical outcomes to advance regenerative medicine. PMID:27766183

  5. The role of magnetic resonance imaging (MRI) in focal therapy for prostate cancer: recommendations from a consensus panel

    PubMed Central

    Muller, Berrend G.; Fütterer, Jurgen J.; Gupta, Rajan T.; Katz, Aaron; Kirkham, Alexander; Kurhanewicz, John; Moul, Judd W.; Pinto, Peter A.; Rastinehad, Ardeshir R.; Robertson, Cary; de la Rosette, Jean; Sanchez-Salas, Rafael; Jones, J. Stephen; Ukimura, Osamu; Verma, Sadhna; Wijkstra, Hessel; Marberger, Michael

    2014-01-01

    Objective To establish a consensus on the utility of multiparametric magnetic resonance imaging (mpMRI) to identify patients for focal therapy. Methods Urological surgeons, radiologists, and basic researchers, from Europe and North America participated in a consensus meeting about the use of mpMRI in focal therapy of prostate cancer.The consensus process was face-to-face and specific clinical issues were raised and discussed with agreement sought when possible. All participants are listed among the authors.Topics specifically did not include staging of prostate cancer, but rather identifying the optimal requirements for performing MRI, and the current status of optimally performed mpMRI to (i) determine focality of prostate cancer (e.g. localising small target lesions of ≥0.5 mL), (ii) to monitor and assess the outcome of focal ablation therapies, and (iii) to identify the diagnostic advantages of new MRI methods.In addition, the need for transperineal template saturation biopsies in selecting patients for focal therapy was discussed, if a high quality mpMRI is available. In other words, can mpMRI replace the role of transperineal saturation biopsies in patient selection for focal therapy? Results Consensus was reached on most key aspects of the meeting; however, on definition of the optimal requirements for mpMRI, there was one dissenting voice.mpMRI is the optimum approach to achieve the objectives needed for focal therapy, if made on a high quality machine (3T with/without endorectal coil or 1.5T with endorectal coil) and judged by an experienced radiologist.Structured and standardised reporting of prostate MRI is paramount.State of the art mpMRI is capable of localising small tumours for focal therapy.State of the art mpMRI is the technique of choice for follow-up of focal ablation. Conclusions The present evidence for MRI in focal therapy is limited.mpMRI is not accurate enough to consistently grade tumour aggressiveness.Template-guided saturation biopsies

  6. Imaging of Intratumoral Inflammation during Oncolytic Virotherapy of Tumors by 19F-Magnetic Resonance Imaging (MRI)

    PubMed Central

    Hess, Michael; Hofmann, Elisabeth; Seubert, Carolin; Langbein-Laugwitz, Johanna; Gentschev, Ivaylo; Sturm, Volker Jörg Friedrich; Ye, Yuxiang; Kampf, Thomas; Jakob, Peter Michael; Szalay, Aladar A.

    2013-01-01

    Background Oncolytic virotherapy of tumors is an up-coming, promising therapeutic modality of cancer therapy. Unfortunately, non-invasive techniques to evaluate the inflammatory host response to treatment are rare. Here, we evaluate 19F magnetic resonance imaging (MRI) which enables the non-invasive visualization of inflammatory processes in pathological conditions by the use of perfluorocarbon nanoemulsions (PFC) for monitoring of oncolytic virotherapy. Methodology/Principal Findings The Vaccinia virus strain GLV-1h68 was used as an oncolytic agent for the treatment of different tumor models. Systemic application of PFC emulsions followed by 1H/19F MRI of mock-infected and GLV-1h68-infected tumor-bearing mice revealed a significant accumulation of the 19F signal in the tumor rim of virus-treated mice. Histological examination of tumors confirmed a similar spatial distribution of the 19F signal hot spots and CD68+-macrophages. Thereby, the CD68+-macrophages encapsulate the GFP-positive viral infection foci. In multiple tumor models, we specifically visualized early inflammatory cell recruitment in Vaccinia virus colonized tumors. Furthermore, we documented that the 19F signal correlated with the extent of viral spreading within tumors. Conclusions/Significance These results suggest 19F MRI as a non-invasive methodology to document the tumor-associated host immune response as well as the extent of intratumoral viral replication. Thus, 19F MRI represents a new platform to non-invasively investigate the role of the host immune response for therapeutic outcome of oncolytic virotherapy and individual patient response. PMID:23441176

  7. Diagnostic Performance of Dual-Energy CT Stress Myocardial Perfusion Imaging: Direct Comparison With Cardiovascular MRI

    PubMed Central

    Ko, Sung Min; Song, Meong Gun; Chee, Hyun Kun; Hwang, Hweung Kon; Feuchtner, Gudrun Maria; Min, James K.

    2014-01-01

    OBJECTIVE The purpose of this study was to assess the diagnostic performance of stress perfusion dual-energy CT (DECT) and its incremental value when used with coronary CT angiography (CTA) for identifying hemodynamically significant coronary artery disease. SUBJECTS AND METHODS One hundred patients with suspected or known coronary artery disease without chronic myocardial infarction detected with coronary CTA underwent stress perfusion DECT, stress cardiovascular perfusion MRI, and invasive coronary angiography (ICA). Stress perfusion DECT and cardiovascular stress perfusion MR images were used for detecting perfusion defects. Coronary CTA and ICA were evaluated in the detection of ≥ 50% coronary stenosis. The diagnostic performance of coronary CTA for detecting hemodynamically significant stenosis was assessed before and after stress perfusion DECT on a pervessel basis with ICA and cardiovascular stress perfusion MRI as the reference standard. RESULTS The performance of stress perfusion DECT compared with cardiovascular stress perfusion MRI on a per-vessel basis in the detection of perfusion defects was sensitivity, 89%; specificity, 74%; positive predictive value, 73%; negative predictive value, 90%. Per segment, these values were sensitivity, 76%; specificity, 80%; positive predictive value, 63%; and negative predictive value, 88%. Compared with ICA and cardiovascular stress perfusion MRI per vessel territory the sensitivity, specificity, positive predictive value, and negative predictive value of coronary CTA were 95%, 61%, 61%, and 95%. The values for stress perfusion DECT were 92%, 72%, 68%, and 94%. The values for coronary CTA and stress perfusion DECT were 88%, 79%, 73%, and 91%. The ROC AUC increased from 0.78 to 0.84 (p = 0.02) with the use of coronary CTA and stress perfusion DECT compared with coronary CTA alone. CONCLUSION Stress perfusion DECT plays a complementary role in enhancing the accuracy of coronary CTA for identifying hemodynamically

  8. Incidental Memory Encoding Assessed with Signal Detection Theory and Functional Magnetic Resonance Imaging (fMRI)

    PubMed Central

    Clemens, Benjamin; Regenbogen, Christina; Koch, Kathrin; Backes, Volker; Romanczuk-Seiferth, Nina; Pauly, Katharina; Shah, N. Jon; Schneider, Frank; Habel, Ute; Kellermann, Thilo

    2015-01-01

    In functional magnetic resonance imaging (fMRI) studies that apply a “subsequent memory” approach, successful encoding is indicated by increased fMRI activity during the encoding phase for hits vs. misses, in areas underlying memory encoding such as the hippocampal formation. Signal-detection theory (SDT) can be used to analyze memory-related fMRI activity as a function of the participant’s memory trace strength (d′). The goal of the present study was to use SDT to examine the relationship between fMRI activity during incidental encoding and participants’ recognition performance. To implement a new approach, post-experimental group assignment into High- or Low Performers (HP or LP) was based on 29 healthy participants’ recognition performance, assessed with SDT. The analyses focused on the interaction between the factors group (HP vs. LP) and recognition performance (hits vs. misses). A whole-brain analysis revealed increased activation for HP vs. LP during incidental encoding for remembered vs. forgotten items (hits > misses) in the insula/temporo-parietal junction (TPJ) and the fusiform gyrus (FFG). Parameter estimates in these regions exhibited a significant positive correlation with d′. As these brain regions are highly relevant for salience detection (insula), stimulus-driven attention (TPJ), and content-specific processing of mnemonic stimuli (FFG), we suggest that HPs’ elevated memory performance was associated with enhanced attentional and content-specific sensory processing during the encoding phase. We provide first correlative evidence that encoding-related activity in content-specific sensory areas and content-independent attention and salience detection areas influences memory performance in a task with incidental encoding of facial stimuli. Based on our findings, we discuss whether the aforementioned group differences in brain activity during incidental encoding might constitute the basis of general differences in memory performance

  9. Bayesian 3D X-ray computed tomography image reconstruction with a scaled Gaussian mixture prior model

    SciTech Connect

    Wang, Li; Gac, Nicolas; Mohammad-Djafari, Ali

    2015-01-13

    In order to improve quality of 3D X-ray tomography reconstruction for Non Destructive Testing (NDT), we investigate in this paper hierarchical Bayesian methods. In NDT, useful prior information on the volume like the limited number of materials or the presence of homogeneous area can be included in the iterative reconstruction algorithms. In hierarchical Bayesian methods, not only the volume is estimated thanks to the prior model of the volume but also the hyper parameters of this prior. This additional complexity in the reconstruction methods when applied to large volumes (from 512{sup 3} to 8192{sup 3} voxels) results in an increasing computational cost. To reduce it, the hierarchical Bayesian methods investigated in this paper lead to an algorithm acceleration by Variational Bayesian Approximation (VBA) [1] and hardware acceleration thanks to projection and back-projection operators paralleled on many core processors like GPU [2]. In this paper, we will consider a Student-t prior on the gradient of the image implemented in a hierarchical way [3, 4, 1]. Operators H (forward or projection) and H{sup t} (adjoint or back-projection) implanted in multi-GPU [2] have been used in this study. Different methods will be evalued on synthetic volume 'Shepp and Logan' in terms of quality and time of reconstruction. We used several simple regularizations of order 1 and order 2. Other prior models also exists [5]. Sometimes for a discrete image, we can do the segmentation and reconstruction at the same time, then the reconstruction can be done with less projections.

  10. Efficient high-dimensional characterization of conductivity in a sand box using massive MRI-imaged concentration data

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Yoon, H.; Kitanidis, P. K.; Werth, C. J.; Valocchi, A. J.

    2015-12-01

    Characterizing subsurface properties, particularly hydraulic conductivity, is crucial for reliable and cost-effective groundwater supply management, contaminant remediation, and emerging deep subsurface activities such as geologic carbon storage and unconventional resources recovery. With recent advances in sensor technology, a large volume of hydro-geophysical and chemical data can be obtained to achieve high-resolution images of subsurface properties, which can be used for accurate subsurface flow and reactive transport predictions. However, subsurface characterization with a plethora of information requires high, often prohibitive, computational costs associated with "big data" processing and large-scale numerical simulations. As a result, traditional inversion techniques are not well-suited for problems that require coupled multi-physics simulation models with massive data. In this work, we apply a scalable inversion method called Principal Component Geostatistical Approach (PCGA) for characterizing heterogeneous hydraulic conductivity (K) distribution in a 3-D sand box. The PCGA is a Jacobian-free geostatistical inversion approach that uses the leading principal components of the prior information to reduce computational costs, sometimes dramatically, and can be easily linked with any simulation software. Sequential images of transient tracer concentrations in the sand box were obtained using magnetic resonance imaging (MRI) technique, resulting in 6 million tracer-concentration data [Yoon et. al., 2008]. Since each individual tracer observation has little information on the K distribution, the dimension of the data was reduced using temporal moments and discrete cosine transform (DCT). Consequently, 100,000 unknown K values consistent with the scale of MRI data (at a scale of 0.25^3 cm^3) were estimated by matching temporal moments and DCT coefficients of the original tracer data. Estimated K fields are close to the true K field, and even small

  11. Patient-bounded extrapolation using low-dose priors for volume-of-interest imaging in C-arm CT

    SciTech Connect

    Xia, Y.; Maier, A.; Berger, M.; Hornegger, J.; Bauer, S.

    2015-04-15

    Purpose: Three-dimensional (3D) volume-of-interest (VOI) imaging with C-arm systems provides anatomical information in a predefined 3D target region at a considerably low x-ray dose. However, VOI imaging involves laterally truncated projections from which conventional reconstruction algorithms generally yield images with severe truncation artifacts. Heuristic based extrapolation methods, e.g., water cylinder extrapolation, typically rely on techniques that complete the truncated data by means of a continuity assumption and thus appear to be ad-hoc. It is our goal to improve the image quality of VOI imaging by exploiting existing patient-specific prior information in the workflow. Methods: A necessary initial step prior to a 3D acquisition is to isocenter the patient with respect to the target to be scanned. To this end, low-dose fluoroscopic x-ray acquisitions are usually applied from anterior–posterior (AP) and medio-lateral (ML) views. Based on this, the patient is isocentered by repositioning the table. In this work, we present a patient-bounded extrapolation method that makes use of these noncollimated fluoroscopic images to improve image quality in 3D VOI reconstruction. The algorithm first extracts the 2D patient contours from the noncollimated AP and ML fluoroscopic images. These 2D contours are then combined to estimate a volumetric model of the patient. Forward-projecting the shape of the model at the eventually acquired C-arm rotation views gives the patient boundary information in the projection domain. In this manner, we are in the position to substantially improve image quality by enforcing the extrapolated line profiles to end at the known patient boundaries, derived from the 3D shape model estimate. Results: The proposed method was evaluated on eight clinical datasets with different degrees of truncation. The proposed algorithm achieved a relative root mean square error (rRMSE) of about 1.0% with respect to the reference reconstruction on

  12. Content-based image retrieval utilizing explicit shape descriptors: applications to breast MRI and prostate histopathology

    NASA Astrophysics Data System (ADS)

    Sparks, Rachel; Madabhushi, Anant

    2011-03-01

    Content-based image retrieval (CBIR) systems, in the context of medical image analysis, allow for a user to compare a query image to previously archived database images in terms of diagnostic and/or prognostic similarity. CBIR systems can therefore serve as a powerful computerized decision support tool for clinical diagnostics and also serve as a useful learning tool for medical students, residents, and fellows. An accurate CBIR system relies on two components, (1) image descriptors which are related to a previously defined notion of image similarity and (2) quantification of image descriptors in order to accurately characterize and capture the a priori defined image similarity measure. In many medical applications, the morphology of an object of interest (e.g. breast lesions on DCE-MRI or glands on prostate histopathology) may provide important diagnostic and prognostic information regarding the disease being investigated. Morphological attributes can be broadly categorized as being (a) model-based (MBD) or (b) non-model based (NMBD). Most computerized decision support tools leverage morphological descriptors (e.g. area, contour variation, and compactness) which belong to the latter category in that they do not explicitly model morphology for the object of interest. Conversely, descriptors such as Fourier descriptors (FDs) explicitly model the object of interest. In this paper, we present a CBIR system that leverages a novel set of MBD called Explicit Shape Descriptors (ESDs) which accurately describe the similarity between the morphology of objects of interest. ESDs are computed by: (a) fitting shape models to objects of interest, (b) pairwise comparison between shape models, and (c) a nonlinear dimensionality reduction scheme to extract a concise set of morphological descriptors in a reduced dimensional embedding space. We utilized our ESDs in the context of CBIR in three datasets: (1) the synthetic MPEG-7 Set B containing 1400 silhouette images, (2) DCE-MRI of

  13. Spatially resolved quantification of gadolinium(III)-based magnetic resonance agents in tissue by MALDI imaging mass spectrometry after in vivo MRI.

    PubMed

    Aichler, Michaela; Huber, Katharina; Schilling, Franz; Lohöfer, Fabian; Kosanke, Katja; Meier, Reinhard; Rummeny, Ernst J; Walch, Axel; Wildgruber, Moritz

    2015-03-27

    Gadolinium(III)-based contrast agents improve the sensitivity and specificity of magnetic resonance imaging (MRI), especially when targeted contrast agents are applied. Because of nonlinear correlation between the contrast agent concentration in tissue and the MRI signal obtained in vivo, quantification of certain biological or pathophysiological processes by MRI remains a challenge. Up to now, no technology has been able to provide a spatially resolved quantification of MRI agents directly within the tissue, which would allow a more precise verification of in vivo imaging results. MALDI imaging mass spectrometry for spatially resolved in situ quantification of gadolinium(III) agents, in correlation to in vivo MRI, were evaluated. Enhanced kinetics of Gadofluorine M were determined dynamically over time in a mouse model of myocardial infarction. MALDI imaging was able to corroborate the in vivo imaging MRI signals and enabled in situ quantification of the gadolinium probe with high spatial resolution.

  14. Generating Super Stimulated-Echoes in MRI and their Application to Hyperpolarized C-13 Diffusion Metabolic Imaging

    PubMed Central

    Larson, Peder E. Z.; Kerr, Adam B.; Reed, Galen D.; Hurd, Ralph E.; Kurhanewicz, John; Pauly, John M.; Vigneron, Daniel B.

    2011-01-01

    Stimulated-echoes in MR can be used to provide high sensitivity to motion and flow, creating diffusion and perfusion weighting as well as T1 contrast, but conventional approaches inherently suffer from a 50% signal loss. The super stimulated-echo, which uses a specialized radiofrequency (RF) pulse train, has been proposed in order to improve the signal while preserving motion and T1 sensitivity. This paper presents a novel and straightforward method for designing the super stimulated-echo pulse train using inversion pulse design techniques. This method can also create adiabatic designs with an improved response to RF transmit field variations. The scheme was validated in phantom experiments and shown in vivo to improve SNR. We have applied a super stimulated-echo to metabolic MRI with hyperpolarized 13C-labeled molecules. For spectroscopic imaging of hyperpolarized agents, several repetition times are required but only a single stimulated-echo encoding is feasible, which can lead to unwanted motion blurring. To address this, a super stimulated-echo preparation scheme was used in which the diffusion weighting is terminated prior to the acquisition, and we observed a SNR increases of 60% in phantoms and 49% in vivo over a conventional stimulated-echo. Experiments following injection of hyperpolarized [1-13C]-pyruvate in murine transgenic cancer models have shown improved delineation for tumors since signals from metabolites within tumor tissues are retained while those from the vasculature are suppressed by the diffusion preparation scheme. PMID:22027366

  15. WE-G-18C-08: Real Time Tumor Imaging Using a Novel Dynamic Keyhole MRI Reconstruction Technique

    SciTech Connect

    Lee, D; Pollock, S; Whelan, B; Keall, P; Greer, P; Kim, T

    2014-06-15

    Purpose: To test the hypothesis that the novel Dynamic Keyhole MRI reconstruction technique can accelerate image acquisition whilst maintaining high image quality for lung cancer patients. Methods: 18 MRI datasets from 5 lung cancer patients were acquired using a 3T MRI scanner. These datasets were retrospectively reconstructed using (A) The novel Dynamic Keyhole technique, (B) The conventional keyhole technique and (C) the conventional zero filling technique. The dynamic keyhole technique in MRI refers to techniques in which previously acquired k-space data is used to supplement under sampled data obtained in real time. The novel Dynamic Keyhole technique utilizes a previously acquired a library of kspace datasets in conjunction with central k-space datasets acquired in realtime. A simultaneously acquired respiratory signal is utilized to sort, match and combine the two k-space streams with respect to respiratory displacement. Reconstruction performance was quantified by (1) comparing the keyhole size (which corresponds to imaging speed) required to achieve the same image quality, and (2) maintaining a constant keyhole size across the three reconstruction methods to compare the resulting image quality to the ground truth image. Results: (1) The dynamic keyhole method required a mean keyhole size which was 48% smaller than the conventional keyhole technique and 60% smaller than the zero filling technique to achieve the same image quality. This directly corresponds to faster imaging. (2) When a constant keyhole size was utilized, the Dynamic Keyhole technique resulted in the smallest difference of the tumor region compared to the ground truth. Conclusion: The dynamic keyhole is a simple and adaptable technique for clinical applications requiring real-time imaging and tumor monitoring such as MRI guided radiotherapy. Based on the results from this study, the dynamic keyhole method could increase the imaging frequency by a factor of five compared with full k

  16. Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

    PubMed Central

    Walia, Shanka

    2015-01-01

    Summary Nano-theranostics offer remarkable potential for future biomedical technology with simultaneous applications for diagnosis and therapy of disease sites. Through smart and careful chemical modifications of the nanoparticle surface, these can be converted to multifunctional tiny objects which in turn can be used as vehicle for delivering multimodal imaging agents and therapeutic material to specific target sites in vivo. In this sense, bimodal imaging probes that simultaneously enable magnetic resonance imaging and fluorescence imaging have gained tremendous attention because disease sites can be characterized quick and precisely through synergistic multimodal imaging. But such hybrid nanocomposite materials have limitations such as low chemical stability (magnetic component) and harsh cytotoxic effects (fluorescent component) and, hence, require a biocompatible protecting agent. Silica micro/nanospheres have shown promise as protecting agent due to the high stability and low toxicity. This review will cover a full description of MRI-active and fluorescent multifunctional silica micro/nanospheres including the design of the probe, different characterization methods and their application in imaging and treatment in cancer. PMID:25821696

  17. Improving Brain Magnetic Resonance Image (MRI) Segmentation via a Novel Algorithm based on Genetic and Regional Growth

    PubMed Central

    A., Javadpour; A., Mohammadi

    2016-01-01

    Background Regarding the importance of right diagnosis in medical applications, various methods have been exploited for processing medical images solar. The method of segmentation is used to analyze anal to miscall structures in medical imaging. Objective This study describes a new method for brain Magnetic Resonance Image (MRI) segmentation via a novel algorithm based on genetic and regional growth. Methods Among medical imaging methods, brains MRI segmentation is important due to high contrast of non-intrusive soft tissue and high spatial resolution. Size variations of brain tissues are often accompanied by various diseases such as Alzheimer’s disease. As our knowledge about the relation between various brain diseases and deviation of brain anatomy increases, MRI segmentation is exploited as the first step in early diagnosis. In this paper, regional growth method and auto-mate selection of initial points by genetic algorithm is used to introduce a new method for MRI segmentation. Primary pixels and similarity criterion are automatically by genetic algorithms to maximize the accuracy and validity in image segmentation. Results By using genetic algorithms and defining the fixed function of image segmentation, the initial points for the algorithm were found. The proposed algorithms are applied to the images and results are manually selected by regional growth in which the initial points were compared. The results showed that the proposed algorithm could reduce segmentation error effectively. Conclusion The study concluded that the proposed algorithm could reduce segmentation error effectively and help us to diagnose brain diseases. PMID:27672629

  18. Improving Brain Magnetic Resonance Image (MRI) Segmentation via a Novel Algorithm based on Genetic and Regional Growth

    PubMed Central

    A., Javadpour; A., Mohammadi

    2016-01-01

    Background Regarding the importance of right diagnosis in medical applications, various methods have been exploited for processing medical images solar. The method of segmentation is used to analyze anal to miscall structures in medical imaging. Objective This study describes a new method for brain Magnetic Resonance Image (MRI) segmentation via a novel algorithm based on genetic and regional growth. Methods Among medical imaging methods, brains MRI segmentation is important due to high contrast of non-intrusive soft tissue and high spatial resolution. Size variations of brain tissues are often accompanied by various diseases such as Alzheimer’s disease. As our knowledge about the relation between various brain diseases and deviation of brain anatomy increases, MRI segmentation is exploited as the first step in early diagnosis. In this paper, regional growth method and auto-mate selection of initial points by genetic algorithm is used to introduce a new method for MRI segmentation. Primary pixels and similarity criterion are automatically by genetic algorithms to maximize the accuracy and validity in image segmentation. Results By using genetic algorithms and defining the fixed function of image segmentation, the initial points for the algorithm were found. The proposed algorithms are applied to the images and results are manually selected by regional growth in which the initial points were compared. The results showed that the proposed algorithm could reduce segmentation error effectively. Conclusion The study concluded that the proposed algorithm could reduce segmentation error effectively and help us to diagnose brain diseases.

  19. Predicting axillary lymph node metastasis from kinetic statistics of DCE-MRI breast images

    NASA Astrophysics Data System (ADS)

    Ashraf, Ahmed B.; Lin, Lilie; Gavenonis, Sara C.; Mies, Carolyn; Xanthopoulos, Eric; Kontos, Despina

    2012-03-01

    The presence of axillary lymph node metastases is the most important prognostic factor in breast cancer and can influence the selection of adjuvant therapy, both chemotherapy and radiotherapy. In this work we present a set of kinetic statistics derived from DCE-MRI for predicting axillary node status. Breast DCE-MRI images from 69 women with known nodal status were analyzed retrospectively under HIPAA and IRB approval. Axillary lymph nodes were positive in 12 patients while 57 patients had no axillary lymph node involvement. Kinetic curves for each pixel were computed and a pixel-wise map of time-to-peak (TTP) was obtained. Pixels were first partitioned according to the similarity of their kinetic behavior, based on TTP values. For every kinetic curve, the following pixel-wise features were computed: peak enhancement (PE), wash-in-slope (WIS), wash-out-slope (WOS). Partition-wise statistics for every feature map were calculated, resulting in a total of 21 kinetic statistic features. ANOVA analysis was done to select features that differ significantly between node positive and node negative women. Using the computed kinetic statistic features a leave-one-out SVM classifier was learned that performs with AUC=0.77 under the ROC curve, outperforming the conventional kinetic measures, including maximum peak enhancement (MPE) and signal enhancement ratio (SER), (AUCs of 0.61 and 0.57 respectively). These findings suggest that our DCE-MRI kinetic statistic features can be used to improve the prediction of axillary node status in breast cancer patients. Such features could ultimately be used as imaging biomarkers to guide personalized treatment choices for women diagnosed with breast cancer.

  20. Comparing deflection measurements of a magnetically steerable catheter using optical imaging and MRI

    SciTech Connect

    Lillaney, Prasheel Caton, Curtis; Martin, Alastair J.; Losey, Aaron D.; Evans, Leland; Saeed, Maythem; Cooke, Daniel L.; Wilson, Mark W.; Hetts, Steven W.

    2014-02-15

    Purpose: Magnetic resonance imaging (MRI) is an emerging modality for interventional radiology, giving clinicians another tool for minimally invasive image-guided interventional procedures. Difficulties associated with endovascular catheter navigation using MRI guidance led to the development of a magnetically steerable catheter. The focus of this study was to mechanically characterize deflections of two different prototypes of the magnetically steerable catheterin vitro to better understand their efficacy. Methods: A mathematical model for deflection of the magnetically steerable catheter is formulated based on the principle that at equilibrium the mechanical and magnetic torques are equal to each other. Furthermore, two different image based methods for empirically measuring the catheter deflection angle are presented. The first, referred to as the absolute tip method, measures the angle of the line that is tangential to the catheter tip. The second, referred to the base to tip method, is an approximation that is used when it is not possible to measure the angle of the tangent line. Optical images of the catheter deflection are analyzed using the absolute tip method to quantitatively validate the predicted deflections from the mathematical model. Optical images of the catheter deflection are also analyzed using the base to tip method to quantitatively determine the differences between the absolute tip and base to tip methods. Finally, the optical images are compared to MR images using the base to tip method to determine the accuracy of measuring the catheter deflection using MR. Results: The optical catheter deflection angles measured for both catheter prototypes using the absolute tip method fit very well to the mathematical model (R{sup 2} = 0.91 and 0.86 for each prototype, respectively). It was found that the angles measured using the base to tip method were consistently smaller than those measured using the absolute tip method. The deflection angles measured

  1. Protein MRI contrast agent with unprecedented metal selectivity and sensitivity for liver cancer imaging.

    PubMed

    Xue, Shenghui; Yang, Hua; Qiao, Jingjuan; Pu, Fan; Jiang, Jie; Hubbard, Kendra; Hekmatyar, Khan; Langley, Jason; Salarian, Mani; Long, Robert C; Bryant, Robert G; Hu, Xiaoping Philip; Grossniklaus, Hans E; Liu, Zhi-Ren; Yang, Jenny J

    2015-05-26

    With available MRI techniques, primary and metastatic liver cancers that are associated with high mortality rates and poor treatment responses are only diagnosed at late stages, due to the lack of highly sensitive contrast agents without Gd(3+) toxicity. We have developed a protein contrast agent (ProCA32) that exhibits high stability for Gd(3+) and a 10(11)-fold greater selectivity for Gd(3+) over Zn(2+) compared with existing contrast agents. ProCA32, modified from parvalbumin, possesses high relaxivities (r1/r2: 66.8 mmol(-1)⋅s(-1)/89.2 mmol(-1)⋅s(-1) per particle). Using T1- and T2-weighted, as well as T2/T1 ratio imaging, we have achieved, for the first time (to our knowledge), robust MRI detection of early liver metastases as small as ∼0.24 mm in diameter, much smaller than the current detection limit of 10-20 mm. Furthermore, ProCA32 exhibits appropriate in vivo preference for liver sinusoidal spaces and pharmacokinetics for high-quality imaging. ProCA32 will be invaluable for noninvasive early detection of primary and metastatic liver cancers as well as for monitoring treatment and guiding therapeutic interventions, including drug delivery.

  2. A permanent MRI magnet for magic angle imaging having its field parallel to the poles.

    PubMed

    McGinley, John V M; Ristic, Mihailo; Young, Ian R

    2016-10-01

    A novel design of open permanent magnet is presented, in which the magnetic field is oriented parallel to the planes of its poles. The paper describes the methods whereby such a magnet can be designed with a field homogeneity suitable for Magnetic Resonance Imaging (MRI). Its primary purpose is to take advantage of the Magic Angle effect in MRI of human extremities, particularly the knee joint, by being capable of rotating the direction of the main magnetic field B0 about two orthogonal axes around a stationary subject and achieve all possible angulations. The magnet comprises a parallel pair of identical profiled arrays of permanent magnets backed by a flat steel yoke such that access in lateral directions is practical. The paper describes the detailed optimization procedure from a target 150mm DSV to the achievement of a measured uniform field over a 130mm DSV. Actual performance data of the manufactured magnet, including shimming and a sample image, is presented. The overall magnet system mounting mechanism is presented, including two orthogonal axes of rotation of the magnet about its isocentre. PMID:27552556

  3. Functional brain abnormalities localized in 55 chronic tinnitus patients: fusion of SPECT coincidence imaging and MRI

    PubMed Central

    Farhadi, Mohammad; Mahmoudian, Saeid; Saddadi, Fariba; Karimian, Ali Reza; Mirzaee, Mohammad; Ahmadizadeh, Majid; Ghasemikian, Khosro; Gholami, Saeid; Ghoreyshi, Esmaeel; Beyty, Saeid; Shamshiri, Ahmadreza; Madani, Sedighe; Bakaev, Valery; Moradkhani, Seddighe; Raeisali, Gholamreza

    2010-01-01

    Tinnitus is often defined as the perception of sounds or noise in the absence of any external auditory stimuli. The pathophysiology of subjective idiopathic tinnitus remains unclear. The aim of this study was to investigate the functional brain activities and possible involved cerebral areas in subjective idiopathic tinnitus patients by means of single photon emission computerized tomography (SPECT) coincidence imaging, which was fused with magnetic resonance imaging (MRI). In this cross-sectional study, 56 patients (1 subject excluded) with subjective tinnitus and 8 healthy controls were enrolled. After intravenous injection of 5 mCi F18-FDG (fluorodeoxyglucose), all subjects underwent a brain SPECT coincidence scan, which was then superimposed on their MRIs. In the eight regions of interest (middle temporal, inferotemporal, medial temporal, lateral temporal, temporoparietal, frontal, frontoparietal, and parietal areas), the more pronounced values were represented in medial temporal, inferotemporal, and temporoparietal areas, which showed more important proportion of associative auditory cortices in functional attributions of tinnitus than primary auditory cortex. Brain coincidence SPECT scan, when fused on MRI is a valuable technique in the assessment of patients with tinnitus and could show the significant role of different regions of central nervous system in functional attributions of tinnitus. PMID:20068582

  4. Functional brain abnormalities localized in 55 chronic tinnitus patients: fusion of SPECT coincidence imaging and MRI.

    PubMed

    Farhadi, Mohammad; Mahmoudian, Saeid; Saddadi, Fariba; Karimian, Ali Reza; Mirzaee, Mohammad; Ahmadizadeh, Majid; Ghasemikian, Khosro; Gholami, Saeid; Ghoreyshi, Esmaeel; Beyty, Saeid; Shamshiri, Ahmadreza; Madani, Sedighe; Bakaev, Valery; Moradkhani, Seddighe; Raeisali, Gholamreza

    2010-04-01

    Tinnitus is often defined as the perception of sounds or noise in the absence of any external auditory stimuli. The pathophysiology of subjective idiopathic tinnitus remains unclear. The aim of this study was to investigate the functional brain activities and possible involved cerebral areas in subjective idiopathic tinnitus patients by means of single photon emission computerized tomography (SPECT) coincidence imaging, which was fused with magnetic resonance imaging (MRI). In this cross-sectional study, 56 patients (1 subject excluded) with subjective tinnitus and 8 healthy controls were enrolled. After intravenous injection of 5 mCi F18-FDG (fluorodeoxyglucose), all subjects underwent a brain SPECT coincidence scan, which was then superimposed on their MRIs. In the eight regions of interest (middle temporal, inferotemporal, medial temporal, lateral temporal, temporoparietal, frontal, frontoparietal, and parietal areas), the more pronounced values were represented in medial temporal, inferotemporal, and temporoparietal areas, which showed more important proportion of associative auditory cortices in functional attributions of tinnitus than primary auditory cortex. Brain coincidence SPECT scan, when fused on MRI is a valuable technique in the assessment of patients with tinnitus and could show the significant role of different regions of central nervous system in functional attributions of tinnitus.

  5. Development of High-Field Permanent Magnetic Circuits for NMRI/MRI and Imaging on Mice.

    PubMed

    Wang, Guangxin; Xie, Huantong; Hou, Shulian; Chen, Wei; Yang, Xiuhong

    2016-01-01

    The high-field permanent magnetic circuits of 1.2 T and 1.5 T with novel magnetic focusing and curved-surface correction are developed. The permanent magnetic circuit comprises a magnetic yoke, main magnetic steel, nonspherical curved-surface magnetic poles, plugging magnetic steel, and side magnetic steel. In this work, a novel shimming method is proposed for the effective correction of base magnetic field (B 0) inhomogeneities, which is based on passive shimming on the telescope aspheric cutting, grinding, and fine processing technology of the nonspherical curved-surface magnetic poles and active shimming adding higher-order gradient coils. Meanwhile, the magnetic resonance imaging dedicated alloy with high-saturation magnetic field induction intensity and high electrical resistivity is developed, and nonspherical curved-surface magnetic poles which are made of the dedicated alloy have very good anti-eddy-current effect. In addition, the large temperature coefficient problem of permanent magnet can be effectively controlled by using a high quality temperature controller and deuterium external locking technique. Combining our patents such as gradient coil, RF coil, and integration computer software, two kinds of small animal Micro-MRI instruments are developed, by which the high quality MRI images of mice were obtained. PMID:27034951

  6. Magnetosomes, biogenic magnetic nanomaterials for brain molecular imaging with 17.2 T MRI scanner.

    PubMed

    Mériaux, Sébastien; Boucher, Marianne; Marty, Benjamin; Lalatonne, Yoann; Prévéral, Sandra; Motte, Laurence; Lefèvre, Christopher T; Geffroy, Françoise; Lethimonnier, Franck; Péan, Michel; Garcia, Daniel; Adryanczyk-Perrier, Géraldine; Pignol, David; Ginet, Nicolas

    2015-05-01

    The fast development of sensitive molecular diagnostic tools is currently paving the way for a personalized medicine. A new class of ultrasensitive magnetic resonance imaging (MRI) T₂-contrast agents based on magnetosomes, magnetite nanocrystals biomineralized by magnetotactic bacteria, is proposed here. The contrast agents can be injected into the blood circulation and detected in the picomolar range. Purified magnetosomes are water-dispersible and stable within physiological conditions and exhibit at 17.2 T a transverse relaxivity r₂ four times higher than commercial ferumoxide. The subsequent gain in sensitivity by T₂(*) -weighted imaging at 17.2 T of the mouse brain vasculature is evidenced in vivo after tail vein injection of magnetosomes representing a low dose of iron (20 μmoliron kg(-1)), whereas no such phenomenon with the same dose of ferumoxide is observed. Preclinical studies of human pathologies in animal models will benefit from the combination of high magnetic field MRI with sensitive, low dose, easy-to-produce biocompatible contrast agents derived from bacterial magnetosomes. PMID:25676134

  7. Structure-function relationships underlying calculation: a combined diffusion tensor imaging and fMRI study.

    PubMed

    van Eimeren, L; Grabner, R H; Koschutnig, K; Reishofer, G; Ebner, F; Ansari, D

    2010-08-01

    Both neuropsychological and functional neuroimaging studies have identified brain regions that are critical for the neurocognitive processes related to the calculation of arithmetic problems. In particular, the left angular gyrus (lAG) has been repeatedly implicated in arithmetic problem solving and found to be most activated during the retrieval of arithmetic facts. While significant progress has been made in determining the functional role of specific grey matter areas underlying calculation, very little is known about the relationship between these activated regions and their underlying white matter structures. In this study, we collected both diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) data while participants performed a mental arithmetic task. Fractional anisotropy (FA) values were extracted from predefined, hypothesis-driven, white matter regions and correlated with fMRI activation values, which were extracted from anatomically defined grey matter regions. Results indicated structure-function relationships on multiple levels. Specifically, a link between the integrity of the left superior corona radiata (SCR) and neural activity in the lAG during calculation was observed, which was found to be particularly strong for problems that have a high probability of being solved via the retrieval of arithmetic facts (problems with a relatively small problem size). The findings reported provide a link between functional activation and structural integrity of grey and white matter regions in the left temporoparietal cortex, thereby contributing to our understanding of the role of both the function and structure of this brain region in calculation. PMID:20382234

  8. A permanent MRI magnet for magic angle imaging having its field parallel to the poles

    NASA Astrophysics Data System (ADS)

    McGinley, John V. M.; Ristic, Mihailo; Young, Ian R.

    2016-10-01

    A novel design of open permanent magnet is presented, in which the magnetic field is oriented parallel to the planes of its poles. The paper describes the methods whereby such a magnet can be designed with a field homogeneity suitable for Magnetic Resonance Imaging (MRI). Its primary purpose is to take advantage of the Magic Angle effect in MRI of human extremities, particularly the knee joint, by being capable of rotating the direction of the main magnetic field B0 about two orthogonal axes around a stationary subject and achieve all possible angulations. The magnet comprises a parallel pair of identical profiled arrays of permanent magnets backed by a flat steel yoke such that access in lateral directions is practical. The paper describes the detailed optimization procedure from a target 150 mm DSV to the achievement of a measured uniform field over a 130 mm DSV. Actual performance data of the manufactured magnet, including shimming and a sample image, is presented. The overall magnet system mounting mechanism is presented, including two orthogonal axes of rotation of the magnet about its isocentre.

  9. A permanent MRI magnet for magic angle imaging having its field parallel to the poles.

    PubMed

    McGinley, John V M; Ristic, Mihailo; Young, Ian R

    2016-10-01

    A novel design of open permanent magnet is presented, in which the magnetic field is oriented parallel to the planes of its poles. The paper describes the methods whereby such a magnet can be designed with a field homogeneity suitable for Magnetic Resonance Imaging (MRI). Its primary purpose is to take advantage of the Magic Angle effect in MRI of human extremities, particularly the knee joint, by being capable of rotating the direction of the main magnetic field B0 about two orthogonal axes around a stationary subject and achieve all possible angulations. The magnet comprises a parallel pair of identical profiled arrays of permanent magnets backed by a flat steel yoke such that access in lateral directions is practical. The paper describes the detailed optimization procedure from a target 150mm DSV to the achievement of a measured uniform field over a 130mm DSV. Actual performance data of the manufactured magnet, including shimming and a sample image, is presented. The overall magnet system mounting mechanism is presented, including two orthogonal axes of rotation of the magnet about its isocentre.